I dove Cozumel twice before and once after the hurricane. Before, most of the reefs were large and nearly pristine, with some reefs reminiscent of relatively untouched sites in Indonesia and the Maldives. Now, as people have mentioned, much of the shallower reefs (reefs above 60ft, such as Paradise, Yucab and Tormentos) are partly covered in sand, are generally smaller and more patchy and many of the corals (both hard and soft) show noticeable signs of damage (breakage). But the fish are just as plentiful as before and Paradise is still just as great for night dives since the creatures you see on such dives include octopi, crabs, lobsters, moray eels, whose numbers haven't been significantly affected. On the deeper dives (over 80ft), such as Santa Rosa Wall, Colombia and Maracaibo/Chun Chakab (if your diveop will take you there), you'll hardly notice any difference. One good thing about the hurricane is some sand that were blown away have uncovered many new swim throughs.
Overall, Cozumel is still one of the best in the Caribbean and has possibly the easiest access (direct flights to Cozumel or Cancun). Other pluses that draw me back include excellent food, shopping, Mayan ruins, reasonable prices, the cenotes, and one of the friendliest, most hospitable people I've met (and many more reasons), which makes Cozumel still my favorite dive destination in the Caribbean.
