Just back from my second trip since Wilma. Did about 6-8 trips before that. ggunn has it right. I did my first shore dive this trip since Wilma (in front of Caribe Blu, at night) and nearly wept as I compared it to what it was like before. But the spots far south (Palancar, Columbia, Maracaibo Shallows aka Chunchakaab) and further north of town are in pretty good shape; make sure the op you are using will take you there w/o extra charges and/or complaints.
I was pleasantly surprised at the improvement to Santa Rosa since my last trip. La Francesca, Delilah, Tormentos, Las Palmas, Cedral and Tunich all produced delights on different days (free-swimming eels out hunting, spotted eagle rays, turtles, sharks, a seahorse, and all the other usual critters). As I was down for a month, I did many of these sites a few times. I did Paradise on a night dive which was great (red eye sponge crabs, freeswimming file clams, slipper and spanish lobsters, sharptail eel) - I don't think it would be a great daytime dive. As others have said, one of the great things about Coz is the people and the lifestyle. But I think that's hard to really get to enjoy/understand if you are in a group and staying at one of the bigger hotels. You really need to be an independent traveller staying in town and Mom and Pop places to really appreciate that.
I think a number of comments about cutting this person loose are well taken. Just how much energy do you want to put into keeping this luser happy during the trip?