I went all in and did an in place upgrade. Everything still works. There's a learning curve but once you get used to it it's quicker to use than 7.
I got my SATA and eSATA drive set as a Storage Space pool and that's awesome. Uninstalled Perfectdisk and cFosSpeed before I dove in, since storage spaces autodefrag, my other disks are SSDs, and the networking is improved over 7. Uninstalled Adobe Reader for Metro Reader just now.
There're a lot of right click actions that you don't expect at first but once you know where everything is it's fantastic.
Metro is undoubtedly not 'pretty' but it gets everything out of the way so you can focus better on what you're actually doing.
My only gripe is Windows Update...switching from Metro to the Control Panel ver for more information is just silly. Not really a huge deal but annoying.
I'd check my WEI score but I'm not really concerned. The drivers aren't final yet so whether it went up or down I'd shrug.
And the game/store apps don't seem to think I'm logged into my WinLive account. Not a deal breaker but keeping me from viewing the extra apps.