The bad thing about Vista is the number of FUD and silly articles it continues to generate. Some would say if you don't like it, don't use it, and move on... clearly they are not in the majority.
As for what people rant about? Same thing as XP, but people forget so quickly. It gets put on PCs that run it like crap (just like those XP rigs with 128mb of ram back when XP was new) and like/dislike of the new look. People also talk about how it is infested with DRM though I have never figured out what that actually means. I guess the ability to play DRM protected content is now = to DRM. None of my media is protected by such junk and I am on Vista.
But yeah that sums up Vista. Lots of whining, not much reason :( I keep hoping it will pass, but no luck so far.