[zbowling]

It's not though. The back button on phones stays on the top or bottom edge (the icons just rotate to face you). Which side it will be on is wild guess though depending on the phone and OEM.

Tablets will move it to the bottom in whatever orientation you are in which good but the issue with that though is that the screen dimensions change and I can't tell you how frustrating that is in games and changing their OpenGL projections on rotation. Not only do you have to handle rotating your content for the orientation, but then you have to adjust for the screen size virtually changing sizes. For some games and apps (like ZenBound) this breaks things by moving the virtual center point of the screen.

[untog]

The back button is ubiquitous for each phone. Yes, it differs between manufacturers but most people only have one phone.

Irrespective of where on the bottom row it is, it's still more useful than the top left of the iPhone 5.