Before I say anything, I'm a Linux/Unix guy, not big into Windows but I use them mainly for games and messaging.
Vista IMHO isn't bad at all, like I said earlier, out of the box it's crippling applicaiton compatability and security, disabling UAC fixed most of that (I can't stand UAC and its popping up access permission every 20 seconds). Difference between the other OS I've used (I've used Windows 2.0, 3.1, 3.11 WG, NT4, 95, 98/98SE, ME, 2000, XP home & pro, Vista 32 & 64), Vista required the least amount of 3rd party programs to make the OS work smoothly, I only have AVG 7.5 whereas my previous XP needed zonealarm, AVG, spysweeper, windows defender and so on. Vista includes alot of self management built-in schedulers and a MUCH better task manager (you can really see what's running and takes you to where they're located on your hard disk if you want to delete the unwanted ones), and games run fantastic on Vista compared to my previous XP. Vista's downside is its network core, it's crappy and can be laggy (hope that gets fixed in upcoming service packs).
I remember all too well how much negative feedback XP got for the first 2 years when it was released back in 2001, everybody hated XP for some reason until SP1 or 2 came out then now everyone worships XP.
As mentioned, Microsoft re-issued XP to new systems because of the feedback on Vista, how come SOE won't do that with SWG and pre-NGE servers?