If there's one thing MS deserves credit for in Vista, it's security. It is the most secure commercial client OS ever made - PERIOD.  The # of vulnerabilities OSX has had plugged since 10.4 absolutely dwarfs Vistas meagre security-related patchs released so far.

But in other areas, it's understandable why people aren't impressed.  Random CPU spikes (especially with TrustedInstaller.exe), way too much disk access, incredibly long boot times until the desktop becomes usable, little innovation in the GUI, etc.  It's a good OS, yes - some of the negative hype are people jumping on the bandwagon.  But it does have the feeling of lacking a coherent design strategy, simply too many cooks IMO.