It's stable and it offers DX10 support. That's about all I really see in it at the moment. I support about 4 users on the Vista platform and it is a bit problematic at times... mainly the compatibility issues with older software (non-gaming software). There still is a few games that have initial issues, but sometimes "compatibility mode" can get around them.
Now I think there is a list or program somewhere that will test all your software / hardware compatibility with Vista which you
may want to run before you upgrade. Then you can know what types of problems to expect when / if you upgrade.
I'd also suggest you read some tweaking guides because there are quite a few services and features that you will likely want to disable after you install. (the auto-defrag is one example)
If I've still got your attention...
Anyways, upgrading will provide minimum performance increases for you (most likely a decrease, especially in DX10), and with the 64 bit OS you need to make sure you are getting 64 bit drivers! I'm not a Vista hater, but I am trying to provide you with as much information as possible from a neutral stand-point.
You've been around long enough to know it's the *exact* same crap as when XP was released: It sucks. My blah~de~blah doesn't run... Resource Hog... Bugs... Bugs... Bugs... Oh My G*D I'm going back to blah blah blah...
Yep, this always happens and will continue to happen. I hate seeing people say how much it sucks when they haven't even used it, but "Saw a video online" or "had a friend of a friend's cousin's uncle" with some Vista incompatibility issue. A particular video comes to mind where this guy tried to install Vista on a 4 year old machine (even if he got it installed - I'd be surprised if it performed well at all) and surprise! it wouldn't install. Of course people always want an easy answer, so no one actually researches or tries to validate the answer on their own... they just spread rumors. (it's easier than backing up your words with facts, right?)