Google’s Android 4.0 operating system is more than just another upgrade.

Android 4.0, also known as Ice Cream Sandwich, marks the start of a new era for Google’s mobile platform. The release ushers in the biggest changes the software has seen since the launch of Froyo in 2010 — maybe even Eclair back in 2009. Nearly every facet of the OS has been made over, and the very core of the Android user experience has been completely reimagined.

The more you use Ice Cream Sandwich, the more you realize just how radical a change it represents.

(Note: For the purposes of this review, I’m focusing on the smartphone side of Ice Cream Sandwich. At the time of this publication, the software had not yet been made available on any tablets.)

Getting to know Ice Cream Sandwich

The first thing you notice when you start using Ice Cream Sandwich is that Android suddenly seems a lot more friendly. While the OS has always been powerful and versatile, simple human relations weren’t exactly its strong suit.
Now, powering up an Android 4.0 device (in my case, the Samsung Galaxy Nexus, which I’ve been testing for several days) is like running into an old college buddy who’s evolved into a slick professional. He has the same smarts, the same heart and soul you’ve always appreciated, but now he really has his act together — and he’s dressing better, to boot.

At a glance, Ice Cream Sandwich seems similar to the Android of years past. You have five home screen panels that hold any combination of app shortcuts, folders and live functioning widgets. Each is made up of an invisible grid that, like previous phone-based versions of Android, can support as many as 16 shortcuts (four across and four down). But beneath that basic shell, ICS is a whole new game.

You can practically see the fresh paint everywhere you look in the system. Gone are the harsh green and black colors of yore, replaced now with a soft blue-and-gray-based scheme. System icons are more brilliant, with bright colors and three-dimensional textures. New transitions and animations are sprinkled throughout the OS, adding subtle but important layers of polish.
Android Ice Cream Sandwich
Ice Cream Sandwich provides a new favorites tray that stays in place at the bottom of the screen. Click to view larger image.

As for the home screen itself, Ice Cream Sandwich provides a new favorites tray that stays in place at the bottom of the screen as you swipe from one panel to another. The tray houses a permanent link to your app drawer along with four customizable icons; you can anchor any shortcut or folder into those spots by simply dragging and dropping it into place.

ICS also introduces a new persistent search box across the top of the home screen. Tapping the main part of the box brings up Android’s universal search field, which simultaneously covers the Web and most content on your phone. Tapping the microphone at right end of the box, meanwhile, brings up Google’s Voice Actions utility, which allows you to conduct a Web search, place a phone call, send a text or email, or get driving directions by speaking into your device.

(Don’t tell Siri, but that’s actually a function Android has had for more than a year.)
The button-free philosophy

Perhaps the most striking shift with Ice Cream Sandwich is its move away from the four physical buttons that have long been Android phones’ most identifiable feature. In fact, the Galaxy Nexus — the flagship Android 4.0 phone — has no buttons on its face whatsoever.
Android Ice Cream Sandwich
Instead of physical buttons, you get three icons at the bottom of the display. Click to view larger image.

Instead, you get a trio of virtual buttons at the bottom of the display: one to go back a step, one to return to your home screen, and one to multitask, or toggle among recently used applications. These buttons will be familiar to Android tablet users; they actually first appeared in Honeycomb, as did an early implementation of the button-free philosophy. But for Android phones, they mark a major shift.

As someone who’s used Android intensely for years, I expected the lack of physical buttons to be a shock. I’m happy to say, though, that I’ve found the adjustment surprisingly painless. It’s really a natural evolution, as the on-screen buttons appear when and where you need them. If you rotate your device to a horizontal position, they move along with it. And if you don’t need them on-screen — say, if you’re viewing a photo or video — they disappear, turning into tiny dots that can emerge when beckoned but stay out of your way otherwise.

That said, the shift in button strategy does change the way you interact with the phone, especially when it comes to the search and menu functions that used to have permanent places on the front of the device. The elimination of the menu function is intended to make Android more user-friendly: Rather than having to press your phone’s menu button to find commands, as you did with previous versions of Android, apps designed for ICS show all your options in a new “action bar” that sits at the top of the screen. The action bar’s commands are context-sensitive, too, so they vary based on what task you’re performing.

When you open Google Voice, for example, the action bar gives you one icon to compose a new text, one to refresh your inbox, and one that holds an overflow list of less commonly used functions (Ice Cream Sandwich’s on-screen equivalent of the old menu button). When you’re viewing an actual message in Google Voice, the action bar changes to give you options to call the person from your conversation or compose a new message to someone else.

This approach is excellent in theory. In execution, however, it has one glaring problem: Ice Cream Sandwich lacks a certain level of consistency with the placement of some key functions. Search, for example, is sometimes an icon in the action bar, and other times an option in the on-screen overflow menu (as is the case in Google Voice).

Even that overflow menu itself moves around somewhat from application to application: On most apps that have been optimized for ICS, it lives within the action bar at the top. But on older apps that have not been updated to reflect the new design standards, it appears squished in alongside the main navigation icons at the bottom. A similar inconsistency occurred within Honeycomb. My hope is that, as the new interface reaches more and more devices, app developers will update their programs to support the new approach.

(With existing phones that have physical buttons, by the way, the physical buttons will continue to function as they always have; you’ll just use those instead of the new on-screen alternatives. The full ICS effect will be seen only on the Galaxy Nexus and subsequent button-free devices.)

The app drawer and home screen customization

Ice Cream Sandwich introduces a newly designed app drawer that puts all of your installed applications and widgets in a single centralized place. The drawer swipes horizontally, with a pleasant scroll-and-fade animation effect as you move from one screen to another. An icon at the top of the drawer gives you direct access to the Android Market as well.

Customizing your home screens is now done right from the app drawer, streamlining a process that used to be far less intuitive. With ICS, you simply touch and hold any app shortcut or widget in the app drawer, and the system automatically shows you a preview of all five home screen panels. You can then drag and drop the item anywhere you want. You can get detailed information about an app or uninstall it while you’re there, too — tasks that used to be buried within layers of settings menus.
Home screen widgets have long been one of Android’s most powerful and distinguishing features, and with Ice Cream Sandwich, they become even more valuable. Following the lead set in the tablet-focused Honeycomb OS (and seen in some third-party launcher replacement utilities), ICS allows you to interact with home screen widgets by scrolling or flipping without having to enter the actual apps.

Noteworthy examples include the Gmail widget, which lets you scroll through messages, and the Photo Gallery widget, which lets you flip through thumbnails of images on your phone. Widgets can now also be resized to take up more or less space on your home screen.

Home screen folders get a makeover with ICS, too, with a fresh new look and highly simplified setup. Creating a folder is now as easy as dragging one app on top of another; you can add or remove more apps by dragging and dropping, and you can change the folder’s name by touching it.
Notifications and multitasking

Ice Cream Sandwich gets a brand new notification bar that houses icons and information about incoming messages and alerts. It’s essentially a prettier and more powerful version of what’s existed in the past.

On the cosmetic side, the new notification area has a transparent gray background with blue and white text, matching the rest of the OS’s revamped design. Functionality-wise, the notifications now support a new system-wide swiping gesture that allows you to dismiss any individual item by flicking it left or right. This is a welcome touch that gives you greater control over what you see.

The Ice Cream Sandwich notifications area includes interactive commands for controlling music playback when the Music app is active. That means you can pause or skip tracks right from the pulldown area, without having to interrupt what you’re doing. Unfortunately, this feature appears to work only with the system Music app at the moment; third-party programs like Pandora are not currently compatible.

Along with the new notification system, Android 4.0 includes a revamped multitasking interface. It’s activated by tapping the new “recent apps” button, located next to the virtual back and home commands. This brings up a scrollable list of all the apps and services you’ve recently opened on your phone, showing each app’s name, icon and a thumbnail of its most recent state. As with the new notifications area, you can tap any item to activate it or flick to dismiss it.

The improvement here over Android’s old system — long-pressing the home key to bring up a small and limited list of icons — is immeasurable. The new multitasking interface is easy to find, fun to use, and a true highlight of the 4.0 platform.
The ICS keyboard and voice input

Google has really gone a long way in improving the system keyboard in Ice Cream Sandwich. Compared to past Android releases, the ICS keyboard is far better at predicting and correcting text, which means you can type quickly and/or sloppily and it’ll almost always figure out what you’re trying to say.
The new keyboard has a few nice bells and whistles, too, like built-in spell checking and a tremendously improved cut and paste system. I tend to be a fan of slide-based keyboards like Swype, but the stock Ice Cream Sandwich keyboard is good enough that I’m actually fine with — and even enjoying — using it.

On the voice-input front, the familiar microphone icon allows you to dictate text anywhere in the system, as it always has — but now, text is transcribed continuously, so words show up as you’re saying them instead of in one big chunk when you’re finished speaking. You can also pause and stop speaking and the system will wait for you to continue instead of stopping the session. (To signal that you’re finished, you press a “Done” button that appears on the screen.)

If the voice input mishears a word or two, error correction in Ice Cream Sandwich is quite easy: The system automatically underlines any words it thinks might be iffy, and then you just tap a word to see a list of likely alternatives and pick a replacement.
You wouldn’t think there’d be much to say about a phone’s lock screen, but with Ice Cream Sandwich, this seemingly simple system component is jam-packed with tasty new treats.

If you don’t set any security options, the default ICS lock screen uses a circular unlock gesture similar to what’s seen in Honeycomb. The lock screen offers a lot more functionality now, catching up with options that some third-party utilities have previously offered.

For example, you can now access and interact with notifications, see album cover art and music playback controls, and jump directly to your camera without ever having to go to the home screen.

Another nice touch: When your phone is locked and you receive a call, the lock screen features a new text-and-reject feature that simultaneously declines the call and sends a message to the person explaining why you can’t talk. You can pick from a list of generic responses or add your own custom message. (You can permanently edit/change the list of default responses by going into the settings section of the Phone app.)
As with past versions of Android, Ice Cream Sandwich gives you the ability to set a security pattern, password or PIN to protect your phone. It also introduces an intriguing new option: facial recognition for phone unlocking. Once configured, all you do is hold your phone in front of your your face. If all goes well, within a second or two, it recognizes your features and unlocks your device.

I found the facial recognition system to be fairly accurate and incredibly satisfying to use. In my tests, the system was able to recognize me roughly 90% of the time, even when I was wearing eyeglasses or a hat or making some silly face (for testing purposes only, of course). The times when it didn’t work were usually when I was in an extreme lighting condition or holding the phone at an unusual angle. But getting your face rejected, while perhaps mildly demoralizing, is not a big deal; you just enter in a backup password or pattern and you’re good to go.

Google does note that the facial recognition option is less secure than a pattern, password or PIN; a disclaimer on the phone goes as far as to tell you that “someone who looks similar to you” could potentially unlock your phone with the feature activated. Some users have reported being able to trick the system into unlocking by holding up a photo of the phone’s owner; I tried and was not able to replicate that. I also tested the system with my brother, whom people often mistake for me, but the phone wouldn’t unlock with his face.

The take-home message: Facial recognition is convenient, novel and impressive — and in most cases, it’s pretty secure. But if you really need to safeguard your data and can’t take any chances, it might not be the right choice for you.

Camera and Gallery

Android 4.0 includes a brand spankin’ new Camera app that’s chock full of surprises. The app’s interface boasts some significant improvements, but the added functions are what really steal the show.
One of the high points is the newly implemented support for zero shutter lag. That means you can snap one photo after another in rapid succession without ever having to stop or wait. It’s actually a little strange at first — and can make it somewhat challenging to get your image focused, if you’re moving really fast — but it’s a fantastic feature that makes photo-capturing easier than ever.

The Camera app has a cool single-motion panorama mode, too, that lets you take wide-perspective images. All you do is tap the panorama icon and press the shutter button, then move your camera slowly across the area you want to capture. When you’re finished, you tap the shutter once more, and the software puts the whole thing together into a single seamless image. It works amazingly well.

On the video side, the Camera app now includes a range of live-video effects — distorting your face, for example, or making it appear as if you’re floating in space. They’re more for fun than anything, but I found they provided some light-hearted amusement while video-chatting with friends. The Camera has a few serious new video-related tools as well, including a snapshot-capturing utility that lets you grab still images while you’re recording video.

The new Camera app and the redesigned Gallery app put photo sharing front and center, with a host of on-screen options to send images to any share-ready service. Ice Cream Sandwich also includes native photo and video editing tools. I found the video editing suite to be a bit limited in its capabilities, but the photo editing options are quite robust, with commands for cropping, sharpening, removing red eye, modifying lighting and making a variety of color adjustments. The photo editor can apply quite numerous special effects, too, if you’re into that sort of thing.
Other Ice Cream Sandwich sprinkles

I could write an entire book trying to cover and review everything that’s new in Ice Cream Sandwich. I haven’t even gotten into the revamped system settings menu — it’s far simpler and easier to use — or the new NFC-based “Android Beam” function that lets you share info with other phones by tapping the devices together (cool in theory, but fairly limited in practice at the moment).

You’ve also got random flourishes like the long overdue ability to capture screenshots and the new fine controls for managing and monitoring your network data usage. Many of the system apps are vastly improved as well, including Gmail, Calendar, People (formerly Contacts) and the browser — which now features faster page loading, automatic Chrome bookmark syncing, offline page saving and graphical tabbed browsing.

But you get the picture. Ice Cream Sandwich is more than just another upgrade; it’s a significant new beginning for the Android platform. It isn’t perfect — the software has a handful of inconsistencies and areas for improvement — but it’s astonishingly good. I suspect it’ll go a long way in delighting both hardcore enthusiasts and casual smartphone users.
Bottom line

Android has always been a powerful platform. With Ice Cream Sandwich, its power reaches new heights — and its polish makes the power more palatable than ever.