I got myself a new phone recently, just to give the newest version of Android a look see. I wanted all the new features available.
No shutter lag, is a great feature. I would always miss the shots I was trying to get due to the lag from the time you clicked the button and the picture being taken. Google addressed this issue with the Ice Cream Sandwich update, now you have the option to make it so that when you click the button it takes the picture right away. Now, one thing I've noticed is that the pictures aren't as good, because the shutter lag allows the camera to focus more, so it's a give and take type of relationship, you might get the picture but it might not look as good.
Face unlock feature. I've only used it to give a test, when Ice Cream Sandwich first came out there was a bug with it, you were able to show a picture to the camera and it would unlock (as long as it was the same person that was set to unlock it in the first place). Google addressed that problem with the 4.1 Jelly Bean update, and there is now an option to make it so you have to blink to get it to unlock, and so far I haven't found a way around that. The feature it self isn't very secure to me, if I wanted in someones phone enough I bet I got get a video where they blinked. I will stick with the screen locks, with the pattern turned off so it's harder to follow what the pattern is.
The updates to the interface include, swipe to close. It is when you bring up your recently opened applications and now you can swipe the apps to the side to close them to help increase your battery life. I use this every day, it helps keep my phone running for a lot longer.
Like always, it is completely customizable to how the user wants it to be. Sure there are a few things that you can't change, but it by far one of the most customizable mobile operating systems out there. You can change you back ground, create folders to keep everything organize (drag one app or file on top of another and it will make a folder). There are a wide variety of applications to allow you do just about anything you can put your mind to, from mobile banking to children games; from cooking books to the latest gossip magazines.