When we dove the Blue Hole in June of last year, it was aboard the Belize Aggressor III. Of 17 passengers on board, my wife and I were among the least experienced, with AOW and crossing the 50 dive mark during the trip. On our departure trip from Belize City, the captain gave a description of the dive and what is involved, then took a vote among the passengers as to whether they wished to make the dive. The captain gave a very detailed briefing, max depth 130 ft, all divers on air (no EAN), if anyone has serious trouble clearing, dive must be aborted to not eat into everyone else's bottom time, 8 min max at depth, 1 min stop at 60 ft, 5 min stop at 20 ft, 3 min stop at 10 ft. If anyone was uncomfortable making the dive, the other option was to buddy up and do a dive on the fringing reef around the hole. No one did.
While I do think this dive was conducted in a safe manor, and all divers that went were qualified to do so, I agree that this dive isn't for everyone. First, it is more of an "I did it" dive than a truly enjoyable dive. The water is a bit cooler than surrounding sites, the vis is lower, the depth is beyond comfort level for many divers, and the scenery is largely rock formations, rather than reefs and fish. Second, it is beyond the training for basic open water students. If you don't have AOW and a fair number of dives under your belt, you should probably wait on this one until you are more at-home in the water.