Just returned yesterday from 9 nights on San Pedro. Did 13 dives, 10 on the barrier reef and a blue hole trip. I was pretty hesitant about the blue hole dive given the many negative reviews I've seen on this board. However, I was thrilled with the dive. Seems to me that attitude reflects some of the responses. If you dive the blue hole it needs to be with an interest and attention to geology as opposed to biology (fish, fauna, coral) that we most often attend to. The stalactites were fantastic, much bigger than I had anticipated; I wasn't quite ready for the thermacline at 120, but after a short bit I didn't notice much.
As others often mention, the 2 wall dives that follow the blue hole are magnificent. The reefs are really lush and abundant with coral and fishes.
I stayed at "the tides" and dove with Patojos on the island, and went with Amigos to the Blue Hole. All were excellent, though I admit to getting a bit annoyed with several dives to tacklebox during our time at the tides. I don't know what the solution is when there are training dives going out with certified divers (not diving together, but going to the same site) because it seems to make the dive locations dependent on the least skilled almost every trip out.
We'll head back to San Pedro next year, I want to dive Turneffe and my partner wants to try the blue hole next time, so it'll be a blast.
Dave