I've been on that site before. Funny thing is that I've only ever seen private classes with 1-2 students going on at the lake. I also haven't seen any dive boats out on the lake. I couldn't find their schedule in the Henderson Happenings newsletter. Even their dive conditions report hasn't been updated since July. Also, Lake Mead is far from being "one of the top five fresh water dive destinations in the United States". I've been to a few of the fresh water dive destinations. I wouldn't even put Mead in the top ten.
They may have a good operation. I haven't dealt with them directly to know one way or another. I have been to a couple of shops in Vegas and the one in Boulder City. The Boulder City shop is the only one that offers hydrocarbon-free air fills and nitrox. It's also the closest to the lake. None of the shops seemed to know much about current diving conditions in the lake. I think they all go elsewhere to dive. Even with the conditions the way they are, if I lived 1/2 hour from there, I'd dive there a lot.
Don't always believe what you read on the 'net. I found a website with a long list of dive sites for Lake Havasu. The site belonged to one of the local shops (not Joel's). We headed out to Lake Havasu and couldn't find any of the sites they detailed. Some of the sites were supposed to be 80+ feet deep. Well, we bought a depth map for the lake and found out the deepest it gets is 40 feet. We also asked Joel (TDL) about diving in the lake and got the real story. In other words, I'm not trying to keep you from diving the lake. I'm just trying to keep your expectations of the lake real.