One of the many attractive features of Linux is the possibility to add beautiful effects to the desktop. Compiz provides the best known set of effects and they can be used both in Gnome and KDE distros. You get this set by installing it from the distribution repositories. However, KDE has its native effects, which are also nice although a bit stiffer: Kwin. (This is Kwin's flipswitch, an application switcher effect that is is also seen in Compiz and in Windows Vista)
However, Compiz also has the Ring Switcher, the Fire-writing, and many other effects. The problem is that some of the possibilities are mutually exclusive. For those who like this kind of eye candy, I'll point out two features in which Compiz and Kwin differ:
1. Different wallpapers in the multiple desktops
As far as I know, this is only possible if you are using Kwin effects. Somehow, the plasma environment does not enable the different wallpapers with Compiz. Here's the desktop display in Compiz. All wallpapers are the same:
A skydome is the animated background that moves as you rotate the cube in Compiz. It is pretty impressive when you have a background image that merges on both sides.
However, if you have Kwin, although you can change the background, you cannot animate it to follow the rotation of the cube. This is the Kwin cube with its fixed background:
Of course, the Compiz set has a lot more effects than Kwin does. Nevertheless, I've seen that Compiz makes KDE unstable in certain computers. Kwin effects, on the other hand, do not seem to cause this problem.
So, if you want to beautify your KDE distro, take this information into account and remember: No four wallpapers if you get skydome. And yes, there are other effects, too, like the ones that Metisse incorporates. However, that is the matter of a different discussion.
Some people consider effects a waste of computer power. They may be right but, in my modest opinion, the cube, the multiple wallpapers, fire-writing, water, and snow make my computer environment more appealing to me. I find this aspect significant because, believe it or not, those pieces of eye candy become quite relaxing when you are trying to write an article on, say, Japanese acceptance/rejection ambivalent syndrome or the dark night of the soul in T.S. Eliot's Four Quartets and the muses decide to hide from you. Plus, when the poor souls trapped in Windows 7 Starter see me enjoying my writer's block by playing with the desktop effects, they always ask themselves why I get so many cool features for free and they have to pay to be able to use the over-rated Aeroshake.