It's OK. My first ever diving experience was there at Dreams Tulum w/ Maya Diving. I was instantly hooked. Dove twice with them, saw some rays, lobster, eels, not too many fish, but both reefs were shallow, about 40 feet or so. But I still loved it because it was the first time. Since then I've been to Playa up north of there a bit and the reefs were bigger and lots more fish. Bigger stuff too, spadefish, barracuda, seahorses, pipefish, etc.
It may be better in Tulum than the places we went but I have heard that it's better up in Playa. In Tulum though you've got closer access to some of the Cenotes which I'm doing in May when I go back down so you've got that going for you!