OK, normally I try to hold off on my enthusiasm for a product until I have test driven it for a while. Even then when I see so many other people saying they like something I hold back even more just to be sure I really do and am not being sucked in by mass-hypnosis. But I have to say without a doubt I really like Vista. Good job Microsoft!
I played around with the beta in its early release form but it was fairly unstable on my test machine. Since then I haven't really used it. I finally loaded it up on my dated laptop and thought, yeah this is kind of neat. But that was the "Business" version. Once I got Ultimate installed on my main system it was a world of difference. Mainly because my main system has a high end graphics card, memory, and processor and all of the bells and whistles could be displayed.
Apart from the new look & feel one of the features I really like is the integration into Windows Update for products other that Microsoft ones. For example, my Infrared Receiver for my Firefly remote was not working and before I had even tested it out I got a notification that Windows had discovered some problems with my system and some potential solutions. Sure enough it directed me to a site to download the new drivers. While installing Visual Studio 2005 the same messages happened. Some might be weary of this since it means that when you install something, be it hardward or software, Windows takes a trip to a MS database to make sure all is well. This could mean that Microsoft records everything as well...although they are most certainly not doing that. No worries though, if you want to disable this, like you most certainly will for managed systems you can follow this article http://support.microsoft.com/kb/931709.
I'm sure I will have other things to add about Vista as time goes on. My main focus will be on using Vista in a managed environment and heading off potential issues before most of us start using it in our businesses.