By contrast, KDE 4.1 requires that I add a "widget" to either the desktop or task panel that I can then use in prescribed and limited ways. The default menu in KDE 4.1 stopped making sense to me and I reverted to "classic view" fairly quickly, though since I never did figure out how to create a task launcher in the panel, I had to tailor the menu to have my most-used programs all together and visible. These issues had me briefly running back to Gnome, but I can't really go back at this point - I like KDE too much. [There were also Ubuntu-Intrepid-level issues (unrelated to KDE) that bothered me, the most annoying of which was that my CD-ROM drive would only mount sporadically. I'm concerned that Intrepid is not up to my high Ubuntu expectations :-(]
Because of all this, I reverted to Kubuntu 8.04 last weekend, and breathed a HUGE sigh of relief. Everything works, everything looks great, and I realized that I needed a fresh install. I hope that the KDE developers will consider keeping a 3.5-level strain of development around for awhile, as I don't plan to try a newer KDE again until at least the end of Hardy Heron LTS support in 2011. . .
UPDATE: Linus Torvalds, original author of the Linux kernel agrees:
I used to be a KDE user. I thought KDE 4.0 was such a disaster, I switched to GNOME. I hate the fact that my right button doesn't do what I want it to do. But the whole "break everything" model is painful for users, and they can choose to use something else.
I realize the reason for the 4.0 release, but I think they did it badly. They did so may changes, it was a half-baked release. It may turn out to be the right decision in the end, and I will retry KDE, but I suspect I'm not the only person they lost.