I downloaded Windows .NET Server RC2 earlier this week. I had RC1 running on my laptop (well, my only machine, really) dual booting with my main OS (WinXP). Because of that, I wasn't really using it much.
I was, frankly, quite impressed. Win.NET Server installed without a hitch, just using the default configuration. Here it is running on my WinXP:
I've only found two small issues with it. One: Installation is slow; it took me almost 3 hours to get everything up and running. Funny enough, it wasn't that my machine was too slow, as VPC was barely using 30% of my processor time. However, performance for the actual OS running seems quite decent to me (better than I expected, frankly). The second issue is that I haven't been able to get the Virtual Switch networking feature to work, and only the NAT option works. However, I think this has to do with the fact that I'm using wireless on my laptop now, and VPC seems to have trouble recognizing the Virtual Switch driver on the wireless card, and trying to use the one on the ethernet port, which was unplugged.
Other than that, it seems pretty cool!