From a GUI perspective I am not impressed. The flat design looks like shit and is harder to use. I have a difficult time finding a button/icon/whatever borders. This is also a problem with their new Outlook/hotmail layout. Ribbon also sucks.
They pretty much made a shitty Classic Shell. Don't see why they can not have drop down menus and Aero as an option. And I believe this will be the last traditional Windows, with future versions being cloud based.