KDE 3.5 -> 4 was its Gnome moment. The fall wasn't as hard, they have come up somewhat from there, but they still don't touch their KDE 3.5.10 Konqueror-primary days. Dolphin was a great example of the rot setting in during those days; Konqueror was the all-in-one browser application and Dolphin was the simplification cancer coming in. THAT particular KDE (which is TDE today) was peak KDE. Yes I am still this buttmad about Dolphin's introduction.

I use XFCE now.