It is hard to say about how good it is because people use different weighting systems for coming up with what exactly is good.
I recently dove Fiji (first time in the Pacific). I really liked it. Decent acropora corals and some soft corals. Most of the fish were on the small side and a bit shy (really nice variety though).
For where we have in common: Belize (Turneffe Atoll), Caymans (Little and Brac), and Turks and Caicos (Grand, South Caicos and Salt Cay). The Caribbean has really good gorgonians, and where healthy large hard corals, great sponges, and the acroporas are Elk Horn and Staghorn (both of which get to impressive sizes, As far as the fish, you get a variety of grouper, snapper, grunts, jacks, blennies, jawfish, hamlets and so on.
Cozumel - is drift diving. The farther south you go on the island the better the reefs. If you stay on a resort in the south, you get short boat rides, There are a plethora of dive ops and most of them are quite good. It is an idea to pay up and get one that does small boats with small groups. Dive masters tend to be quite good. Because it is drift diving, people tend to sight see and look more at the big stuff. The macro stuff is there is you slow down and look for it. The dive masters on the last op, actually found nudibranchs fairly often. The routine is drift until you get low on gas and then go up and do your safety stop. The last group had an early group and a late group (they put two dive masters in the water. Oh, and most of the dive ops know each other and look out for each other. I have popped up with the boat nowhere in sight but there has always been someone else nearby (rarely happens, the boat captains are very good at following bubble). It is just a matter of asking them to give our boat a call and it will come over,
At Cozumel, the corals in the south can be pretty good but the diversity is kinda low. You can see some nice larger fish. It is not as good as some places but it is better than many. You will also usually see turtles, nurse sharks, sometimes a reef shark and so on. Oh and it has the unique splendid toad fish which is a really cool looking critter. You will usually see several during a trip if you have a good dive master.
Unlike many places, Cozumel has a very good restaurant scene. The resorts can have great to good food, You can get a taxi into town and hit a restaurant and then go back to the resort. Diving is usually 2 dives per day. Some places you can do another dive.
Last time I went, was in August. The currents were pretty mild (well except once for part of a dive). So that was nice. Before that, we went in April and the currents could go up to ripping. Usually it was fine but sometimes it was fast enough as to make diving a bit challenging as far as looking at things (unless you managed to duck behind a coral head).
So it is not my favorite place to dive in the Caribbean. But it is well worth going to.
