I'm not one to fiddle with the appearance of my Mac's UI. I think Apple did a pretty good job, and I see no reason to change it. That being said, certain parts of OS X's default appearance can be a little inconsistent, and the custom UI theme called UNO was designed to make OS X consistent across the board. UNO 1.5 has just been released, and it is a complete rewrite of everyone's favorite OS X theme. If you want to banish Brushed Metal from your Mac, or just like the look of the so called 'Unified Toolbar,' then UNO is worth checking out.