Well running one from MSDN.
Start screen - okay. But not when you need to select something from Control Panel. On Windows 7 - you type disk management and press enter. Win 8 - disk management, down, down, enter, enter... Regression is NOT nice.
Why I need disk management on Win 8? Because double clicking vhd shows error message - "Sorry, there was a problem mounting the file". Inane...
Aero transparency gone? Bullshit, extended Aero frame on our software was epic. And I liked it. Oh wait, but there's transparency on the taskbar?

So inconsistent...
Talking about taskbar - on main monitor there's no "combine", aka wide USEFUL taskbar buttons. On second monitor - they're always combined... Well, atleast FINALLY windows has a taskbar for second monitor.
Altho it's pretty fucking useless, when you click on taskbar's shortcut on SECOND monitor and windows 8 launches it on FIRST monitor /head-desk... Scratch that, miles away below custom solutions on Linux, still pretty decent.
These are my nitpickings after using for an hour.
Also, how the fuck do I close Metro applications besides task manager? They're all uninstalled now anyways, because they're so unbelievably useless...
Also, some random five icons when closing a window are fucking annoying (that shit from introduction video).
Task Manager is nice, Explorer is nice, Copy Dialog is nice. That's about it. Still mad on myself that I went the usual "clean install" upgrade route. :< If I would have installed alongside Windows 7, I would have used Windows 7 'till Windows 9 came out (or just ditch Windows entirely for Arch Linux, as I did with Windows XP and Vista pre-SP1 <- failures like Windows 8 ).