FWIW, I just got off the phone with a knowledgeable Samsung rep. I've ordered, but haven't recieved my case yet and I was going to process the return before I even got it based on the replies to this thread.
The rep said they had an employee meeting, specifically about this case, where a number of employees were given the phone and a case to try and install it. He said that nobody got it installed correctly on the first try.
There is apparently a trick to installing this case. The rep I spoke to was VERY specific when telling me how to install it. Lay the phone screen facing up in the bottom half, line it up, then PAY CLOSE ATTENTION to the "little tabs" when you line them up. He said that in order to install it correctly, you're supposed to line up and snap the bottom tabs first, then push "inward and upward", towards the AT&T logo to get the top tabs to correctly come together. He said that if you do it wrong, the tabs will break.
I am holding off on processing my return until my case ships to me and I have a chance to try installing it correctly.