I notice that iOS apps tend to have buttons where you press at all corners of the screen. Many Android apps are pretty much lazy ports of iOS versions of apps. They still have these buttons in the corners instead of using the menu and back buttons on the bottom of Android phones. On my Galaxy S3, it is more difficult to reach the far corner of the screen with my thumb while using the phone one-handed which I find annoying. On a more properly designed app, the menu and back buttons at the bottom of the phone should be used. It would make it easier to use these apps one-handed on a larger phone.
If Apple makes phones approaching 5" and beyond, I think that it would make it more difficult to use these apps one handed. Perhaps, they may need to rethink their guidelines on button placement in apps. I know I don't like having to reach far corners of the screen if I have to do it a lot. Having a large screen is nice as it is more comfortable to look at. It's OK for far corners to display information, but not if you have to tap the far corners a lot.
