personally the gui theme drives me nuts, the lack of aero affect has dragged it back a decade. PC's have been pushed back to put them in line with tablets, effectively to try and make tablets a more attractive option to use. Win8 is so ugly I may as well install linux which is free, faster and will likely have a more stable UI design in future updates.
The fonts and cleartype is rolled back in win8 also so it doesnt display so well on a pc led as win7.
Plus is dozens of minor gui features removed which do add up.
Metro cant be completely ignored as some of the dialog boxes on the desktop are metro themed as if they half converted to metro (not sure if bug or intentional).
BT Infinity 2 Since Dec 2012 - BQM