I dove with Amigos Del Mar and was very pleased with the service. Personally I suspect they are among the better dive opporators on the island.
I did not like the island that they used for lunch on the day trip to south Turneffe.
The regular crew at town was better then the crew that took us to the Blue Hole (they were kids, really, the ones that took us to the BH).
Other then those two things, which I suspect one will run into with pretty much most shops, I was pleased with Amigos Del Mar. The regular (town) crew were very friendly, laid-back people who at the same time conducted themselves well as divemasters.