I first used KDE in about 1997/1998 (when I managed to compile KDE1.0beta on Solaris at Deutsches Elektronen Synchrotron (DESY)), and have used it often since on Linux systems. I followed the early KDE development mailing lists, and have done some Qt development under KDE. KDE definitely made machines running Linux far more comfortable to use.

(I now work mostly under Mac OS X, without KDE.)