It's that good.
I'll be honest: I actually like Windows 7. I've run the Release Candidate in a virtual machine that simulated netbook hardware and it worked fine. It was stable and snappy and it's certainly the best Microsoft OS to date in my opinion. My oldest son has been using it non-stop with absolutely no trouble (except the lack of printer drivers for our home printer) since late July and I can certainly say that if I bought a new PC with Windows 7 installed, I wouldn't just repartition and toss on Linux. I'd dual-boot, of course, but that's because I like Ubuntu, not because Windows 7 is a bad OS.
However, Ubuntu has something going for it that Windows 7 doesn't: Netbook Remix (NBR). A whole lot of us in Ed Tech are rolling out netbooks; they're incredibly cheap and do almost everything our students and teachers need them to do. Intel's Classmates actually add value with their touch interface in ways that standard laptops cannot at very aggressive prices. Netbook Remix is optimized for small displays and, to a lesser extent, for low-powered processors.
While I've been using Ubuntu NBR version 9.04 on my Lenovo S10 quite happily, I installed the beta of 9.10 last night (via a simple upgrade) and I'm really glad that I did. Not only is the visual interface even more streamlined and better suited to the small screens of netbooks, but the performance is quite snappy. Karmic Koala has been reviewed extensively elsewhere, so I won't bother here.
It's not my point to review it. Rather, because so many of us in Ed Tech have compromised on screen size and performance to get computers into more students' and teachers' hands, Karmic Koala (and previous versions of NBR) help us compromise less on the computing experience. NBR doesn't try to look like Windows; it doesn't have to. Rather, it is a purpose driven version of a solid OS that fully exploits the resources of the netbooks we have deployed.
Karmic Koala is quite stable now and worked out of the box with my machine (standard netbook fare). It's fast, attractive, and highly usable, with easier software installation and the nicest interface I've seen on a small screen. If Windows 7 included a polished netbook-specific interface, this might be a different conversation, especially with Microsoft's new free antivirus products. Until then, though, it's NBR for me and at least a dual boot for my netbook users so they can give it a spin.