The newest Google Android operating system, called Ice Cream Sandwich, was debuted Wednesday on the much-anticipated Samsung Galaxy Nexus, which is intended to rival the newly-released iPhone 4S. As Hayley Tsukayama reported:

Smile! It’s the quickest way to unlock your phone.

Straight out of sci-fi, Google and Samsung unveiled an unlocking mechanism based on facial recognition as one of several new features of the long-anticipated Galaxy Nexus. The companies showed off the new phone — the first to come with Android 4.0, Ice Cream Sandwich — late Tuesday at an event in Hong Kong.

Galaxy Nexus users will be able to do away with passcodes and other security measures, though the phone itself warns you that it’s not exactly the best option. In Google’s introduction video, a screenshot of the phone says the feature is “low security, experimental.” The feature didn’t work in Google’s on-stage demonstration, either: while the phone didn’t unlock when it saw a stranger’s face, it didn’t seem to recognize its owner, either.

The Galaxy Nexus has a ton of other features as well, including voice typing, baked-in Google+ integration with hangouts and Messenger and the ability to take a panoramic photo with a single motion. Some were disappointed that the phone didn’t have the drastically curved profile Samsung hinted at in its promotion images for the phone, though the new phone sports the same “contour design” of the Nexus S.

Other specs for the phone include a slightly slower-than- expected 1.2 MHz processor and a “high-end” camera with a 5MP resolution. As CNET’s Jessica Dolcourt pointed out in her hands-on writeup from the event, that spec is a little puzzling, since Samsung has put 8MP cameras in its Galaxy S line. Then again, the companies said that this phone has better camera software, which may make up for the lower resolution.

Many analysts see the combination of the Galaxy Nexus and Ice Cream Sandwich (ICS) as powerful enough in computing power and usability to challenge Apple’s newest smartphone. Joshua Topolsky reviewed ICS on the Galaxy Nexus and wrote:

The new software is striking. I’m in love immediately. Everything in the OS has been touched by the designers at Android. Nothing looks the same.

Along the bottom of the homescreen you have a “favorites tray,” which can be customized, in the center is a button to get to your applications. Google search is always present on homescreens in the launcher, kind of like “Just Type” in webOS. When you want to create a folder now, you simply drag an icon onto another icon, similar to iOS. Inside folders, app icons will rearrange themselves, also like Apple’s software. Widgets can scroll and be resized, as in Honeycomb. Everything is smooth and fluid; new animations have been added throughout the system.

The multi-tasking icon pulls up a list of app snapshots similar to Honeycomb, but those applications can now be killed by swiping them to the right — like vertical cards. Gestures are all over ICS. “Gestures are much more fun than hitting buttons. Touching and moving things; way better than buttons,” Matias says while moving around the device. Even the calendar app didn’t escape the touch treatment; you’re now able to pinch-to-zoom on your schedule to expand or contract the view, which seems incredibly helpful.

The notification window is now slightly translucent with a glowing dot when you pull it downward. Notifications can be swiped away one at a time, mirroring webOS 3.0 behavior. You can access your notifications on the lock screen if you’re not using a passcode, and you can jump quickly to your settings through the window shade.

Applications like Gmail have been completely redesigned. Gone are hidden menus — they’re now replaced by contextual menus which change with your selections, similar to Honeycomb. But on the phone things feel more complete, easier to reach, they make more sense. “We’ve taken all the hidden stuff away,” Matias says. You can swipe left to right to move backwards and forwards through your messages. There’s a new inbox selection chip at the top of the screen, but still no unified Gmail inbox. “It’s harder than you think,” he tells me.

In Gmail, Google Talk, and elsewhere, there’s a real push to use left-to-right swipes to move from place to place — very similar to the recent versions of the Market and Music applications Google has released.

The keyboard and text selection has been hugely improved. You can now long press anywhere on the phone to select text, and you get a contextual menu for copy, paste, and sharing options. Matias says he’ll put the ICS keyboard up against any other virtual keyboard on the market in terms of accuracy and correction.

There are new apps and features too. A “People” application works as your contacts list and a way to gather all of your friends social network activity. There are APIs which developers can plug into to harness the app’s power. It’s somewhat reminiscent of Microsoft’s people panels in Windows Phone 7. I ask Matias if this is a replacement for the address book. “The concept of an address book or contacts feels so lame and dated, it’s like ‘an address book is this little thing with this faux leather cover!’”

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