I stayed there for a week a little over a year ago. Assuming the same people are running the dive op. The resort is nice especially for the area. You should know, however, that there is not much to do as far as outside entertainment is concerned. Don't expect Cozumel or Playa del Carmen type attractions. It is basically the resort and that is it at night.
Rooms are well done with AC. They do cut off the electricity but it is long after you are asleep so no problems with being uncomfortable. All of the tap water, including the showers, is generated at the resort so no worries in that department. They have a large bar (that is the Mayan pyramid building) for the evenings. Food is by a set menu and was pretty decent. Not gourmet but was good. Lunch was eaten on the boat (sandwiches).
The dive op has a nice 48 foot boat that makes the crossing to the Banks in about an hour and a half. Usually do 2 tanks on the Banks and the 3rd dive coming in on the barrier reef close to the resort. The staff was very laid back and let us dive our own profiles. They were a fun group to go out with. All of our diving was "drift" diving so whereever you came up they would come and get you. Tank fills were around 2900 psi. Ask them to take the group to the fish camp for lunch one day. There is a fish camp where some local fishermen live in shacks built inside the lagoon. So after our 2nd dive we motored over and tied up to one of shacks where the fishermen had prepared fresh lobster, fish and conch for us. Very cool and was interesting to see how these guys live.
As for the Banks diving, very healthy reef. Huge sponges, lots of black coral (at fairly shallow depths)and all of the usual carribean marine life (except pelagics). There is little or no current and the diving is fairly shallow. There are not deep walls like Cozumel. The best way I can descibe it is pristine. Visibility was around 60 feet. Since there is little current, it does not have the visibility of Cozumel. However, it does not have the busloads of divers of Cozumel either which helps explain its pristine condition. The week I was there we did not see any other divers. The inshore reefs were pretty good as well. Not as healthy as the Banks but good. Typical spur and groove formations. We did see a lot of lobsters and turtles on the the inshore reefs as well as Eagle Rays on two different dives.
All and all, Maya Ha was a great trip. It is somewhat remote which for me was a plus. A nice place to get away from it all. I love this part of Mexico and would go back. I just hope it does not go the way of PDC. The resort can arrange fishing or Mayan ruin tours as well. I did not go on the tour but the people in my group who did said it was very nice.
Nearest chamber is in Belize.
Are you taking a charter bus or the regular bus service to Majahual? I had an interesting bus journey myself.