Pros:
- Feels great, I prefer the slight sponginess the cover gives vs. the bare keys
- Nearly invisible (the backlit keyboard shines through perfectly)
- A near perfect fit
- Provides great protection against grease, grime, dust, and spills (although i have not tested the spills :p)

Cons:
- Gets cloudy as it gets dirty. Shows it is doing its job, I guess, but it does need to be washed with dish washing liquid and water every few weeks to keep it completely transparent. I made the mistake of washing it with soap and water the first time, which made the cloudiness worse. I later learned from their customer service that washing with hand soap indeed makes it worse and to use dish washing liquid instead, which worked perfectly.
- Seems kinda pricey for a thin sheet of rubber, but worth every penny! Nothing else on the market except that silicone stuff, you get what you pay for I guess =)