It's several steps back
I'm sorry but the new UI is just terrible. I went in willing to give it a shot (which I'm sure some of the zealots won't believe) but nothing is intuitive. I stumbled around and had to force several shutdowns before find how to switch apps or even worse how to safely power it down. The likes of OS X may seem prehistoric but I went from being a windows user to slipping into the likes of both OS X and Ubuntu with a few minor blips to do with more advanced stuff. I don't feel like I have a clue what I'm doing with Metro.
On top of that most of the Metro apps require signing into a Windows Live account. I don't do that crap on my day to day OSes and I'm not about to start now.
Snow Leopard user here as I wasn't exactly enamoured with Lion.
It could have been something really interesting but instead it's just a mess. I fail to see how new users are meant to simply pick it up (something I did with iOS as an example). Maybe it works better with a touch interface but don't make it a desktop OS then.