@ManipUni: I think it's a lot more than the battery. The UI is polished and fit for purpose, that's the main selling point.
 

You're absolutely right there is far more too it. As I see it you have two competitors:
 - Cheap Android (poor battery - useless device)
 - Expensive Android (relatively poor UI, design, build quality)

Android devices are between a rock and a hard place. If they charge too much people will naturally compare them to the iPad and lose. If they charge too little they have to pull features which people see as staples of a good tablet (like >6 hours battery).

There is a razor thin gap where Android will sell well.

PS - I don't take Windows 7 "seriously" as a tablet OS. Nuff' said.