Totally disagree. I hopped from OS to OS for over a decade every other year or 3 (Win, OSX, Linuxes with various DMs/WMs) and it's always, always an adjustment period from "WTF is this" to "totally productive with this now", usually a matter of 1-2 weeks. Happy with Fedora/Gnome right now but have to say just Explorer itself beats Finder and Nautilus (rebranded as "Gnome Files" apparently now) for keyboard users when it comes to out-of-box file managers.
The weird new tiles/metro UI stuff they tried pushing from Win 8 is of course a pretty bad attempt to Microsoftify the "secondary desktop layer" concept that has been prevalent on the other OSes for longer, and better. It sucks, but also useless and thus not used for many/most power users I'd guess.
The rest of the "UI" question is in the hands of individual independent app developers, as it properly should be.