I have downloaded Windows 7 and installed the x64 version on my Dell Latitude D820 last week. My experience is this:
4 GB, Core 2 Duo 2.0 GHz, 200 GB – 7200 RPM drive.
Install: < 30 minutes from CD in drive to Login
Boot-up: < 20 seconds from Off to Login
The only thing I found wierd is that when I went to join my domain at home, I had to configure my network card to have the IP Address and to have the domain name as the default connection DNS suffix. Then I could join my domain, otherwise, it would give me an error and I could go no farther. (bug)
The other thing is that when I was away from my network and had no network connectivity, it logged in very fast (something that Vista is not doing for me).
The other things in the UI as far as grouping or Libraries, and the concept of a Home Network group was pretty cool.
Anyway, my experience has been good, I have installed Visual Studio 2008 with SP1 and SQL 2008 on the laptop and VS 2008 launches amazingly fast and SQL 2008 runs well too.
Overall, I give this a 9 for experience, as I have burned a DVD from ISO with no additional software or anything and it all worked. The only thing I wish that it has was the ability to browse an ISO and use it as a drive without another piece of software. I installed MagicDisc on the machine and it hung everything when I went to access the DVD ISO.
Have fun with it, I plan on taking it through the motions.