I installed it as a dual boot setup on my laptop with Windows 7. I skipped the developer preview so I can't comment on changes, but so far I despise what I've seen. Unless they allow you to get rid of the stupid Metro UI I'll stick with Windows 7. I've been considering going Mac OS for some time, Microsoft might just have made the decision easier for me.
While it might be fine for tablets, I think it is very cumbersome as a desktop operating system. I realize most of the Metro "Apps" are "Preview" versions, but they look horrid so far IMO. I swear some of them look like they were designed in Paint, just like the fish logo they have right now. The calendar magically links itself to Google, but randomly decides which of your calendars to show. Mail linked itself to my GMail without asking permission and attempted to sync. This might make computing "easier" for the clueless user, but for people who know what they're doing it seems like a major nuisance.