All I know, if anyone dares say Unity or Gnome Shell 3 is great yet Windows 8 is terrible, they should be... well, bad things should be done to them.
IMO Gnome3 / Unity is probably even worse than windows 8. At least with Windows 8 you still sorta have the regular UI, it's just that almost everything you try to do, or if you move the mouse a certain way that registers as a gesture, it throws you back into metro. With Gnome 3, it just boots right into "metro" and there's no alternative place to go. I lasted about 5 minutes with it and uninstalled it. I later on decided I should give it another chance, I lasted 2 minutes that time. Hitting the alt + F keys to get a console session was more intuitive than trying to use that UI.

The part that pissed me off the most is if you do manage to find a way to open an app, it just takes over any thing else you may have had open. There was no real way to switch between existing opened apps. Completely horrible design. Even Linus Torvalds himself had some pretty nasty things to say about it.
Thankfully there are distros like Linux Mint that use a more traditional UI. I have to hand it to Microsoft because the traditional Windows UI, say windows 2000 era or XP with "classic mode", is probably the best GUI ever and if everything can continue to mimick it, it will be a good UI. The minute you try to steer away from it, it's less usable.