Dangerous? How about massively increasing the time it takes to do basic administrative tasks. I've spent so much time trying to do things in Server 2012 that were absolutely simple from NT 3.5 to Server 2008 that I am officially now rebelling against their stupid Metro interface. Everything is fucked up.
Try debugging an L2TP VPN connection using the silly new interface - you pass from old school to Metro to old school to Metro three times. It just ain't worth it.
They can make a new UI, but nobody's gotta accept or use the damn thing.
Even that Windows 8.1 laptop I was talking about in my parent post: I messed with that for two months. Two days ago I reloaded the thing with Windows 7. I have work to get done, don't have the time to mess with the latest Microsoft fad. Good riddance to bad rubbish.