Windows 8 was fine for me as well. I did a straight upgrade yesterday from 7 and went v smoothly. Only problems were...
1) Wifi card did not work, had to uninstall and re install drivers. It kept defaulting to old drivers.
2) USB3.0 intel driver was reported as not compatible. 8 Instructed me to uninstall during upgrade. Win 8 has built in drivers. That worked fine.
3) alan wilsons win 7 xv5050 driver did not work. So had to disable driver signing in settings menu. Actually quite easy to do once you know how and potentiall very useful.
4) A500 pro did not work , so just downloaded win 8 drivers from roland and all working fine.
5) repeated - choose your browser message on startup which has now gone after i installed firefox.
If on win 7 there is no reason to upgrade on a desktop, but at £25 until 31/1/2013 no reason not to really if all your drivers are available. Mine came free so i thought i would try it out. I dont really care for the start screen much and how it manages closing windows, full screen apps, file management etc etc.
I do like the live feeds and the dashboard approach to the smart screen when not using x2 and taking a break etc. I have set the smartscreen up with shortcuts to folders, programs etc. But the quality of free apps available is not great and many of them dont work properly.
This vid pretty much sums up my feelings on it, including the marginal gains in performance for some DAW tasks. It is windows 7 to all intents and purposes with an iphone interface which you can turn off easily and work like you would in windows 7. All my VSTs/maschine/tetra/minubrute etc all work fine which is a relief.
http://www.youtube.com/watch?v=kPix1QK9Hb4