First, the rubber tactile covering makes it more comfortable to type on. Second, the white on black print covers up those smudges. And finally, I chose the large print option which makes the individual keys easier to identify.
For Mac users, you can get custom keyboard covers that offer shortcut hints for all kinds of programs like Photoshop, Final Cut Pro, and more! And they support just about every MacBook and keyboard Apple makes, or recently made.
Still, I think I'll clean that keyboard, and then put the cover on to keep it clean going forward! The KB Cover is washable so that's nice and will not just help keeping things looking nice but with the spread of germs.
KBCovers.com has a 20% off show special running for 15 days after Macworld ended, 1/282012 if you enter SHOW2012 at checkout.