I haven't had any problems with it not locking in the back. It is a pretty tight fitting case, little bit bulky but that is great for drops. The only problem's I have had are:
1. It does not fit in the multimedia dock.
2. When I tried to take off the part that is attached to the slide out keyboard, it kinda separated the rim around the phone. It just snapped back into place. I was worried when it happened, but once I snapped it back together it was fine.
Do you know of any cases that fit the multimedia dock?