The iphone 5 is big enough, I would not buy anything larger than that, its a phone, not a tablet!
Ive always said that, but ive had the 5 since the release day and i think it could do with being a little larger, edge to edge would be nice, maybe an extra inch in screen size without increasing the size of the phone too much.
I am a bit of an apple fan boy, but i feel they are behind the other phone companies when it comes to what they can do, although i believe alot of it is due to the software being so restrictive. iOS 7 looks like a jump in the right direction, but im sure itll still be far to limiting!
I never see them sinking and disapearing as they are very innovative, they just choose to not release their best stuff for some reason