Visited Maya Chan for the first time just one week ago. Of the week-long Norwegian cruise, this was by far the best place we visited. The beach and establishment are very clean, the food was better then anything we ate on the ship, the drinks kept flowing, and the second you meet the owners you feel like you've known them forever. I chose to sit in a beach chair for hours while my husband and teenage son kayaked, snorkeled, and got massages. It's the best of both worlds at Maya Chan - you will not be disappointed!
Scary in the city - get out of the city and head to the mountains. We did cave tubing (not booked through the cruise line) and it was alot of fine and beautiful. But Belize City itself does not have anything to offer - it's unsafe and the guides will tell you this. But seeing the armed guards with the huge assault rifles at the drug check points will convince you too.
Beautiful place - my son scuba dived (through the ship) and loved it. My husband fished (not booked through the ship - Victor Bodden tours) and he had a blast, even though they didn't catch the "big one". I just walked around and shopped and felt completely safe - even after I ventured through the "white gates" into the unprotected areas of the port. Lots of the family went snorkeling and then to a beach (booked through the cruise line) and they said the snorkeling was beautiful and the beach was a blast.
Third time at Cozumel - it's just so touristy. We counted 7 cruise ships there that day - need I say more? If I have to port there again I will definitely do some type of excursion just to get out of the hectic city and actually see a beach, as I have yet to see one, but I hear they do exist. It's just not a short walk away.