I've been taking Windows 7 for a spin and kicking its tires, which was relatively painless. Installation went quick, smooth without any bumps and I was quite impressed with how quickly it boots up. If eye candy is your thing, then Windows 7 definitely has it, building upon the Aero interface with the new addition of the tuned up taskbar. One of the things that I really thought was cool with the windows that have a progress bar (think installations, copying of files, downloads etc), the progress would reflect in the app in the taskbar. What this means is that you can be copying an item and have the progress window covered, and know it's coming along. The eye candy kinda wears on me though, so I found myself turning the Aero glass off and switching to a much more opaque theme. I think all the transparency is distracting, but that's maybe because I am still using Windows XP.
Copying small and large files didn't suffer from the usual Vista hangs and eternal copy times, which was a welcome relief. Application launches seemed pretty snappy, though I didn't take any hard numbers to be able to compare to both XP and Vista.
One of the downsides I experienced was lackluster performance on video games. It was reporting 100+ fps on Team Fortress 2, but the visuals said otherwise. Despite any performance enhancing tricks I pulled (dual core hacks, adding 2GB of RAM, etc.), I could not get it to perform very well. To be fair, I installed Vista Ultimate SP1 with the same settings and it did a much better job.
UAC, the much maligned "Cancel or Accept" prompts were noticeably muted in this release. Apple really got them on that with their 'I'm a Mac' commercials, but I personally didn't seem to mind. You fire up any common Linux distribution and you'll see as many, if not more such prompts in order to make any root required changes.
Final verdict? Well, I'm going to wait and see. I know that more betas ought to be coming down the pike and with Direct X 11 still in beta mode itself, I'm going to reserve judgment until the release candidates or a gold disc to really see if Windows 7 is for me. I find it promising that Microsoft is starting to listen to its user base, creating an OS from user requirements (performance and stability) instead of marketing 'air castles and flying ponies'. We'll see what year-end or early next year brings us.