KDE used to be a very nice desktop environment for Linux, I remember using it over the years in CentOS, Fedora Core, Kubuntu, Mandriva, and PCLinuxOS. I used KDE 3.5.x in Kubuntu and thought it was the best desktop environment available for the Linux operating system. But lately things have gone downhill.
I'll start with Dolphin. The KDE desktop used Konqueror as the default file manager up until KDE4 when the KDE project replaced Konqueror with the Dolphin file manager. Konqueror was a feature-rich file manager that can double as a nice web browser, although not as good as Firefox. It has since been replaced with Dolphin, which is no where near as feature-rich as Konqueror. Why would someone take a feature-rich application out and replace it with an application which doesn't have a comparable set of features? Were the KDE developers bored and needed something to do for the next couple of years? I feel that the KDE developers should have left Konqueror as the default file manager, kept Dolphin out of the release, and written a new web browser comparable to Firefox.. this would have made KDE an even better DE.