Compelling Metro apps
I have asked Windows 8 user after Windows 8 user (and the few Surface users I could find) about what good Metro (uh, Modern UI) apps there are out there. The universal answer: none.
I'm writing this on Windows 8 right now, and I have access to the entire Modern UI Windows store. I tried to find a good text editor, but they all sucked. Not just mediocre, but terrible. So I'm happily using my traditional Windows desktop applications -- fine for desktop use, but not a compelling tablet app solution.