I did a casemate for my 4s, and ditched it after a few months. On the case I got (looks similar to yours), a really cheap thin black rubber condom goes over the phone and then you slip that really flimsy piece of plastic over it. The rubber is annoying because the bottom piece by the home button starts to become loose over time and gets to be very irritating.
After two months or so the background that I put on the case started peeling, and by the time I traded it in the case was completely white (peeled) around the edges. Piece of crap.