We went from xp to 7 at work and everyone hated it at first, mostly just having to learn something different. Now that we have been using it for almost a year everyone loves it and would never want to go back.
Have no problems here with Windows 7 Ultimate. Had it for about 2 years now and got used to it fairly quick. Run it in custom built 10 TB tower for my non-compressed blue ray movies and music for the Surround Sound theater next room over. Mostly use workstation for my contracting businesss though.