I'm one of those folks who runs Windows on my laptop out of habit, but I'm not passionate about it. I run Ubuntu on my server, and am happy with that, and have considered moving to Mac OS just so I can have one of those cool, shiny Apple Powerbook notebooks.
I hadn't been thinking upgrading from XP to Vista, but I bought a new Dell laptop earlier this year, and it came with Vista, so I said 'Why not?'. Six months later, I am among the legions of people who are unimpressed with Vista. It's not that it's worse than XP, but Microsoft have changed a lot of things, and virtually none of them are for the better.
For example, XP used to give you the choice whether to sleep, turn off, or restart; and if you pressed the shift key, the sleep option would change to hibernate. In Vista, the corresponding menu has no hibernate option. This is a nuisance, because I dual boot my laptop, and I use hibernate a lot.
And so on. The whole thing felt more sluggish than it should, given that I'd moved to a laptop 3x more powerful; and there were other niggling things, nothing broken exactly.
I thought I'd give them chance to redeem themselves with Vista Service Pack 1 (SP1). I resisted the temptation to try SP1 Beta in September, but when they released the Release Candidate.
I just installed the Release Candidate (RC) of Vista SP1. The upgrade took about an hour, as they warned, but otherwise went smoothly. Vista and most apps work fine, but in two hours I have had problems with the usually impeccable PerfectDisk (offline defrag doesn't work) and Google Desktop (has crashed twice so far).
Given that post-SP1 Vista isn't noticeably different (they may have shuffled the fields of the wireless connection dialog around, I'm not sure) and a couple of apps have problems, I'd recommend that you don't install SP1 until it's officially released.
I can't blame Microsoft when two apps that they don't control have problems in a release which isn't production. But over the past ten years, we have grown accustomed to the new release always being better than the last. I'll have to revisit that assumption. And for future Microsoft products, I'm downgrading my rating from 'sure, let's give it a try' to 'skeptical'.