Looks too clean. Had to tidy my desktop to match. 
. I'm guessing it'll fit in better when we get the final WIndows 8 UI, as it kinda stands out a bit.
As a heavy Outlook/OneNote / light Excel user here's my thoughts:
Liking EAS support in Outlook (so long Hotmail Connector). Losing push, and decent performance was the main trade-offs when I moved my SBS2003 account over to Hotmail. Hopefully this will be better, although performance seems to be off 2010 levels at the moment.
ClearType looks broken in Outlook - probably down to IE not supporting/using ClearType on Windows 8. If one thing gets sorted, I want it to be this. I don't care about losing ClearType in Metro, but I bad-looking text in the desktop mode is starting to do my head in.
Don't like that the To-do view calendar mode only shows today's appointments... How about showing the next couple regardless of what day it is like 2010 did.
Had to squash the big menu down the bottom, as it looked silly, luckily only took about 30 seconds to figure out how.
OneNote is OK... I don't like how I can't seem to have notebooks listed vertically down the side, now they're just horizontally listed, or minimized.
First thing my other half said when she saw it was I don't like (pointing at all-caps tabs). Same thing we saw back with Visual Studio - some people might not get on with it. I'm coping.
So lots of niggles at the moment. But I haven't gone back to 2010 yet!!! 
