I have spoken to many people who dislike KDE solely based on its default appearance, the Air/Oyxgen set of styles and themes. Some have even argued that it looks too much like Windows (although evidence strongly suggests that Windows 7 mimicked KDE, rather than the other way around). What those people may not realize is that you can make KDE look as much like Gnome or any other desktop environment as you want. The customizations in this guide are just examples. They will not give an exact Unity or Gnome appearance, as most people change those defaults anyway. Instead, this example will use some of the common customizations that Ubuntu and Gnome users often apply.
The Desktop Theme
KDE-Look has a plethora of desktop themes you can use. To change your theme, do the following:
The Window Decoration
Since you are already in Workspace settings, now is a good time to change the window decoration. If you want to really be like Ubuntu/Mac OS X, you can move the window buttons to the left side:
Application Appearance
Getting the application appearance you want is a little more tricky. That is because KDE does not currently offer users the ability to install new styles from within System Settings. Therefore, before you choose a style, you will need to make sure the one you want is installed. You have two options: 1. You can install the actual GTK style that you want and use it, or 2. Find an actual KDE or Qtcurve style that matches the one you want. If you decide to go with the Qtcurve option, you can download something like Ambiance-like. Download it and extract it to the folder of your choice. To install it, do the following: Alternatively, you can use the Ambiance color scheme from KDE-Look.
Panel and Launcher
In most distributions, the KDE panel is at the bottom and is rather large. To move it to the top: KDE can use a global menu that works for KDE, Qt, and GTK apps. To use it: You have a couple of options for launchers. You can either use a KDE-native launcher like Daisy or Fancy Tasks, or you can use a separate launcher program like Docky (mono-based but very reliable), Plank (fast, light-weight next-gen Docky), AWN (robust and powerful), or Cairo Dock (all about options).
Icons
KDE uses a slightly different icon theme system from Gnome and Ubuntu. Therefore, it may not be the best idea to use those themes directly, but they will still work. The alternative is that you can find one specifically modified for KDE. Faenza-Cupertino is a very popular iconset for Ubuntu users, and KFaenza is an excellent KDE version. To install it:
Mixing and Matching
You are certainly not limited to the examples I have shown. You can mix and match whatever you like to get your KDE desktop looking exactly the way you want.
