I dove there in January and had a great time. There is some reef, but it's not spectacular. There are lots of animals of all sorts. The coastline there is exposed to the wind and when it picks up, they close the harbor, so you are more likely to lose diving days to weather than you are in Cozumel, where the diving is principally on the leeward side of the island. At PDC, you also have the option of diving the cenotes, sinkholes leading to underground rivers. It is basically guided cavern diving for open water divers. It is pretty interesting if you are really comfortable with your buoyancy skills. Just about all the shops in town have cenote diving. I went with Yucatek. They were very good for the cenotes. I dove one day in the ocean with Abyss. They were pretty good, but have small boats. I dove a couple of days in the ocean with Tank Ha. They run a good operation and they use somewhat larger boats. You will still be in a group of six divers or less (I think eight is their max), but you have a little more room to gear up and it's more comfortable. PDC is a fun place and the diving is certainly worthwhile, if not spectacular.