I will definitely have to test-drive the new "improved Desktop" before committing to Win8. What I can't shake is the fact that the ability to switch isn't enough. I want to be able to completely turn off the new interface, and keep my PC's performance optimum. Windows has had huge issues with RAM-eating in the past (Vista requiring a minimum of 2GB RAM to function in any way is a good example).
If history is any indication, wait for Win9:
Windows 95 was innovative and groundbreaking, but completely broken. Windows 98 set the bar extremely high.
Windows ME was innovative, but glitchy and broken in many ways. People stuck with 98 until XP rolled around.
Windows Vista was new and flashy, but literally the worst OS of the 21st century. Vista remained top dog until Windows7.
Now here comes Windows8. I'll let the tech-junkies beta test that thing, and wait until Windows9 (or whatever it's called) in 2013/14.