I tried the Kubuntu version yesterday and I wasn't impressed. I guess I don't get how it's supposed to work. The window switcher is neat, but why not show what programs are open, instead of just how many? The tabs? at the top seem like an after thought and the launcher makes no sense.
In full disclosure I'm a KDE user(running KDE4 on my desktop, since 4.0) but I am a big UNR fan. Ubuntu's gnome based netbook remix just seems perfect and well thought out for netbooks, although I think they may be moving backwards with 9.10.