Downloaded KDE 1.90 over Friday/Saturday night (wonders of free net calls - even if it does drop the line every 2 hours, something which a retry on wget doesn't mind about).
Built; hit problems. It works fine if you let KDE take over your entire system by letting it start its window manager etc, but not if I just want to run some apps under Gnome - no keyboard input.
Having said that, running it in KDE domination mode seems to work fairly well. Koffice is promising - I wrote a set of slides in kpresenter and it only crashed a few times. (The fact that it stores documents as gzip'd tars of XML files is great when you have to go out and fix something it screwed up).
You can see the result at: www.treblig.org/talks/xfree4