I'm one who switched back. I still have my MBA and carry it while traveling since its so damn light, but when I have work to do win7 just seems more efficient. menus anchored on the top are archaic, and I hate the dock it just seems a disorganized mess to me. in comparison, jump lists and multi monitor on Win7 are just more efficient IMO. there are some good things, I really love exposé. but I'm also wondering about the design direction of Mac software, with all the physical world metaphors like making a desk calendar complete with ripped pages for iCal (how many people under 60 have used a desk calendar?).
that said, I ordered my iPad this week with the engraving "your time is limited. don't waste it living someone else's life."