Here are my brief impressions of it so far:
Installation
Requires that Vista be on the machine in order to upgrade to Windows 7 Beta. Otherwise, you have to do a clean install. Unfortunately, you have to attempt the illegal upgrade before you get the message that tells you this. If Microsoft is trying to get people to let go of XP, letting them upgrade from XP directly to Windows 7 might be a good idea. Otherwise, the install was pretty straightforward.
IE8
Disappointing. It can’t render http://www.vmware.com correctly, so I couldn’t download VMware Player from the site. I had a copy on a flash drive fortunately, and was able to install from there. Firefox works just fine (so far).
Virtual Machine
It looks like there’s some sort of permissions thing preventing me from running them. Adding the VMWare Player created an additional user on the machine. When I tried to open the VM I already had, I got some odd sort of permissions error.
Drivers
Windows 7 Beta detected the biometric scanner on the Lenovo T61 I’m using and directed me to the most current driver. Once I “enrolled” my fingers, it worked just fine. It didn’t have any trouble at all with the SanDisk Cruzer Micro 2GB I’m using either.
Miscellaneous
The way Windows 7 handles active program icons in the start bar is rather clever, though it still retains the unfortunate multi-function button for logging out, switching users, shutting down, etc.
More impressions later as I play with the operating system more. This version of the beta doesn’t expire until August 1, 2009.