I'm on the W7 beta. My experience is that it works better than Vista on lower powered machines. For example, it runs well on my old 1.1 GHz TabletPC where Vista was a hog. I think they're targetting it to run well on Netbooks.

I don't have a problem with Vista and much prefer it to XP on an appropriately beefy machine (GF and I both have quad cores with 4 GB RAM running x86). I can't remember one BSOD or other significant problem with it. Looks great on a 24" LCD.

There are a couple of odd things about W7 like they took out Windows Mail (used be called Outlook, you can download Live Mail or another client). I still don't understand why the full PC backup isn't in all versions. I have it in Vista Ultimate and it should be a basic part of any operating system, IMO.

There will be more codec support in W7 including H.264:

Windows 7 codec support - Neowin Forums

This is a big win since most users will not need codec packs which are a common vector for malware.