It will be hard for me to change the mind of someone that believes it to be too deep and short a dive to look at a few stalactites and a number of sharks.
However, if you do a search on my nickname with the keyword Blue Hole, I believe you will find a font of info that I may not be able to successfully recreate here. Be sure to put in a long time limit for capture of my posts.
I've been in the Blue Hole a number of times, and even though everytime I come out of it, I'm saying "Again, again, I want to do it again!", I could probably forego it anyway, just to be able to do a third dive on Halfmoon Caye Wall or Lighthouse Wall. Unfortunately, there's no day trip offering that.
I've been on the Turneffe day trip a number of times, and comparitively have truly enjoyed it only half the time.
There's just something so special about the Blue Hole day trip, most especially if you get good weather for it. It's not just the Blue Hole, which I still love to do, it's lunch on Halfmoon Caye, Halfmoon Caye itself and the two followup dives are just fabulous, especially when the viz is just right. For example, as you drop down at Halfmoon Caye Wall, there's a large patch of white sand below and you can see the multiple criss-crossing tracks made by the conchshells. At that point, the quality of the water color can not be described (by me anyway). Once the group is assembled, you will head towards the wall. The divers, one by one, slip through a break in the coral heads, and suddenly, there you are out over the wall, looking out and down at the blue. I've had some magnificent dives on that wall, including a solitary experience with a single spotted eagle ray. We bonded and swam together for quite some time. Of course, I got heck later from the DM for not staying within sight of the group, but I wouldn't have given up that experience for anything.
A fish and a bird can fall in love, but where will they build their nest?