Possible game-changer: FaceTime video calling with the ability to switch between front-of-phone and back-of-phone views on the fly. (Something I wish the Flip did.)
Possible game-choker: Battery life. They tout 40% more battery life thanks to a bigger battery. I’m guessing you’ll need it. Recharging after every FaceTime call would suck.
I think a lot of people will wait until the whole AT&T marriage sorts itself out. If that honeymoon is, indeed, over and iPhone opens to Verizon and other carriers, it’s game over for every other smartphone.