Username or EmailPassword
Presumably you've some insight as to what this "TON of positive feedback" from it's "target audience" consists of and who they might be.
Far as I can figure it consists wholly of those who'd be quite happy with an iPad instead (not as well as)of a computer. It's a large market, but it's not nearly as inclusive as the one MS has now. It's not even as if they couldn't have both.