Unlike other reviews here, I actually did not like this product. It's simple enough to put on - you'll be worried you're going to tear it stretching it over the controller, but it's fine as it is elastic!
I actually found the silicone to have a rather greasy feel to it and it was not as pleasant as holding the controller as it comes.
Also, because the skin has a thickness (albeit negligible) it does impact on the ease of which you can access the L1, R1, SELECT and START buttons, as they subsequently become a little bit more recessed.
After using it for 1 game of Black Ops online, I took it back off and will be sticking it on ebay!