KDE4 is eye-candy. But most of the distributions that bundle it are not that stable or usable. Here I don't talk about PCLinuxOS 2010 or Mepis 8.5. They have done a great job in their implementation of KDE 4. But there are a lot others.
Well, coming to the point.... Of late I planned to install a KDE-only Debian desktop on a custom-made system. It was meant for somebody very new to Linux. That's why I thought of good old KDE 3 and the most stable distro of our times - Debian Lenny. Lenny installed a fully-functional KDE desktop on that machine (PIV on Intel 945 mobo) quite well. Afterwards I made some tweaks on the system so that my friend could easy plug his ntfs external drive, web cam, use his stock DVDs, windows media files and so many other non-free stuff. Again after configuring debian-multimedia it was easy as always.
KDE 3.5.9 on Lenny worked like a charm - quite responsive while carrying a truck load of kde apps. But those gtk apps looked butt-ugly on a kde-only environment. Here is a screenshot of how a gtk app looks on a debian pure kde desktop.
As you see, the look of apps is not consistent. Thank God, there is gtk-qt-engine package in Lenny repo. I installed this package and configured in kcontrol (kde control center) as shown below. And Lo! Upon reboot I got consistent KDE look across kde and gtk.
If you are also a KDE-lover but can't do without some gtk apps gtk-qt-engine is the way to go.
Here is the screenshot of Avidemux after installing gtk-qt-engine.