I have one in the 255xxx range and it's perfectly fine. There is a little oil slick on the screen, but I had that on my iP4 also. Considering I work in hydroblasting, the LifeProof is perfect being that it's waterproof and shockproof. I've dropped this off of the second level of a chemical plant and the only damage was a few scratches on the case. Call quality is fine and the other end doesn't have any issues either. The only complaint I have, and I had it for the iP4, is the call volume in the ear piece is a little lower but that is due to the waterproof membrane covering it and there isn't much, if anything they can do about it.
Overall, if you can get one in the 255xxx+ range, I would highly recommend it. The first one I had was 164xxx and it was garbage with the pillowing and back plate issues.