Version:            (using Devel)
OS:                Linux
Installed from:    Compiled sources


System Settings, on my humble opinion, is a step forward in the right direction, however, it seems to be too cluttered and wasting too much space, a screenshot:

http://www.suse.de/~dmacvicar/screenshots/kde4-system-settings/1.png

Doesn't look bad? Let's see the System Preferences on Mac OS X:

http://www.suse.de/~dmacvicar/screenshots/osx-preferences/leopard-preview-prefs-24.png

System Settings windows size is 690 x 521, while System preferences size is 615 x 423. Yet, OS X implementation is showing 26 options against 16, and, looking less cluttered and easy to understand at the same time.

I think KDE devs could take a hint from Mac OS X system preferences, and reduce the space between items, and changing the way it separates sections (because it's wasting much space too).