Software: The preinstalled Linux (Xandros?) is crap, so I immediately installed the Ubuntu 10.04 netbook remix. I have to say that I am extremely impressed with Ubuntu. There is a nice application launcher (in place of a traditional desktop.) The window manager uses the "one maximized application at a time" model, which I initially thought would be annoying, but is actually really nice. Each running app gets a small icon on the panel, and Alt-Tab switches between apps. Very good use is made of the limited (1024x600) screen real estate. I found it easy to add a new application launcher (for Eclipse!), and to add launchers to the "Favorites" category. Connecting to wireless networks (WPA and WEP) worked flawlessly. Installing software from the package repositories (openjdk, subversion) worked great.
Hardware: Awesome! The screen is bright and sharp. The keyboard is much better than I expected - I can type at close to full speed. The track pad works very well, and dragging on the right edge scrolls up and down. I haven't run any benchmarks, but it seems quite responsive. I installed Eclipse and did a bit of Java programming, and performance was fine. (It's some kind of Atom which supports hyperthreading.) Battery life is predicted (by the Ubuntu battery meter) at about 5.5 hours, which seems reasonable. I am waiting for a 2GB memory module to arrive, but with the pre-installed 1GB it works just fine. And the size - it really is significantly smaller and lighter than any traditional notebook, even ultraportables.
Overall: I really like it a lot so far. I'm looking forward to seeing how well it can handle serious work during the school year.