I got this case at the Sprint store and have been pretty happy with it. The combination of the hard plastic outside and the silicone inside seems to offer a lot of protection, and there is a nice lip to protect the screen. All the holes seem to be in the right places and the buttons work well. The power button is a bit difficult to press, but I actually like this as it prevents it from being accidentally locked in my pocket (it only there were a way to disable the Sense ring lock).
It does make the phone noticeably bulkier, especially on the back where the case bulges out a bit (there is a 1mm gap between the phone and the case. Still, the overall package is no thicker than my naked HTC Hero. The added side thickness also means that the phone doesn't stand up as much when using the kickstand.
The store only had the white version, unfortunately, but since I was exchanging another case I didn't have much of a choice (it was that or the pink Otterbox Commuter).
I've removed it a couple of times and had no problems with the back cover coming off, but I was careful to follow the removal instructions (at least on the Sprint version, it comes with instructions telling you to remove it starting with the bottom corner next to the microphone, followed by the other bottom corner, following by sliding the top out). It fits the car dock well with the insert removed and with some minor adjustment of the foam pads.