[Photon]

Let's not forget to include the fact that it has considerably increased battery life. It has a much higher quality screen(In-Plane Switching) with increased pixel density. Performance will increase and multi-tasking will be handled by A4 in such a manner that it won't devastate battery life, which is currently a problem with multi-tasking on other OS' like Android.

The included gyroscope and accelerometer will likely prove to be useful for Augmented Reality applications.

I also like the fact that it will include cameras on the front and back, as well as dual microphones for ambient noise cancellation.