@carl well, KDE 3 (maybe even 3.5) was out when I first switched to Linux (coming off of WinXP). So a tabbed file manager, integrated shell, the ability to view images/PDFs without having to open another window were all new and great. Then KDE 4 landed pretty rough. It's probably a lot of unwarranted nostalgia, I also had a lot more free time to mess with things back then.
One thing I don't miss: manually modifying my xorg.conf