I've been on KDE since coming back home to Linux a few years ago. A few thoughts:

* KDE feels like we just kept on iterating on the same UI since the early 90s. The functionality is very deep, but also intuitive. A lot of the depth comes from things like KIO, kparts and dbus, where we see a lot of functionality being reused from one app to the next. This means if you learn how Konsole works, when you fire up a terminal in other KDE apps, it works the same way.

* Customization is really a good thing. Everyone isn't learning to use a computer for the first time. Computers have been personal for almost 50 years now.

* Would really love kmail and the whole korganizer get a refresh. It's really good when it works, but needs some crashy-ness and jank removed. (BTW Akregator, the KDE-PIM RSS feed reader is still EXCELLENT)