I've seen mentioned that the new GNexus pentile-based display isn't as good as the GS2's.

Android 4 is looking super slow and unresponsive, hopefully they'll address that - though it's an issue that has been around since the first Android version.

Face detection is one of the best features of the whole release - once it's working properly. I didn't watch the video for this part to see how responsive it was, but not having to type a passcode is pretty cool. I hate typing passcodes and would much prefer to just be able to slide the unlock button on the phone while it analyzed my face to determine whether it should actually unlock or not. I wish iOS 5 had introduced this.

Screen size can be evaluated quantitatively however. There are certain things you can and can't do given a certain sized screen. The importance of the interaction to any one individual is definitely subjective however. But that doesn't matter when you're designing a product that you would like to sell millions of.

I hope the iPhone 5 comes out with a slightly bigger form-factor and larger screen, but I sincerely hope all those rumored dimensions and models go in the trash bin. I'd like the next phone to be as brick-like in design as the iPhone 4. In fact I'd love to see precisely the same design cues, simply adjusted for size. No scallops nor curved backs. No difference in height between chin and forehead.