The dives are highly structured, actually a little more so than I like, but I understand the reason for it.
The first time you dive Bonne Terre, you must go on "Trail 1," which starts with the entire party descending to about 30' immediately upon entering and demonstrating buddy breathing and mask clearing to the dive master. When I initially heard this, I was a bit put off by this waste of time: after all, here I am, Rescue Diver certified, having to show that I was certified once upon a time. However, in gearing up, it came up that 2 of the member of our dive group hadn't dived in about 3 years. There was another little sub-group of 3 fellow, one of whom asked the dive master for help in setting up his equipment...he didn't know which direction the regulator should face when installed!! After seeing that, I was actually glad we did the skills check.
The dives themselves are conducted by a dive master, whom you must follow like a little puppy. The mine is somewhat sporadically lit and the dive master has the only light in the group, so following him is actually quite a good idea.
I only went on two dives at BT, but both of them were enjoyable. There are a number of remnants of the mining operation left over for you to look at and marvel about. However, at $60 a pop, as fascinating as it was, I'm not sure I'll be back anytime soon. But it's something you should do once.