I bought one on ebay as well. Maybe it's just my luck, mine works fine, both the front and back cover stays on. I am not sure what the previous poster means by it's not rubberized, mine pretty much feels like the back of the shift but a bit more smooth/less rubbery, if that makes sense.
It does make the shift thicker, but to me it makes sense because it protects the camera lense & screen when you put the phone flat on a surface. But it does make the power button harder to press when I wasn't used to the case. FYI it's about 2mm thinner than the Seidio case, according to my measurement against the measurement someone posted for the Seidio case.
The only thing I don't like about it is that there is a slight bow on the right side of the front cover. You can't tell by looking but it doesn't stay against the side of the screen and there's a slight give when you press on it.