I have been an active Ubuntu user for 6 years now. I have been using its default desktop. It is stable and has some advantages but it is also a bit boring.
A week ago I switched to Ubuntu 13.10 64-bit, still in alpha.The KDE version is 4.11 and is working very well.
What is good about KDE (k)ompared to standard Ubuntu unity desktop?
1) Looks: Looks way better than Unity/Gnome 3. On par with Linux Mints MATE desktop.
2) Plasmoids: They work way better than in earlier versions of KDE 4.X. I use:
* favouries launcher: Gives a nice application start menu when right clicking on the desktop
* yaWP: Weather prediction
* Some of the built-in plasmoids for CPU, MEM, DISK, NET monitoring, Folder viewer etc
3) Yakuake. Drop down shell. Press F12 and it is there. Again and it is gone.
4) Clementine: Great looking music player
5) Dolphin: Great file manager. Nautilus is also good, but Dolphin has some advantages.
6) Krunner: Press Alt-F2 to start applications or use any of the plugins
7) Short-Cuts: CTRL-ESC for task manager, CTRL-Alt-Esc for kill window.
What is missing:
Some bugs (alpha of Ubuntu). More apps should be based on QT instead of GTK2 in my opinion. Example: Firefox, Filezilla, Shutter, Wine (Gtk2 right?), IBM Notes etc, apps that I use everyday. That would offer a better looking desktop experience and less resources would be needed.
Favourites launcher: http://kde-apps.org/content/show.php?content=117639