Just back from a week in Cancun and wanted to report on a few restaurants. All in all it was a great trip, with some surprisingly good meals.
Best of the best: La Habichuela--located in downtown Cancun--take a cab, it's hard to find. Make sure to eat in the garden--it is beautiful. I had the cesar salad prepared table side, touristy yes, but yummy; fish with a tomatoe sauce--good too. Others in my party had the chauteau briand (sp?) and shrimp in a coconut shell--well enjoyed.
La Parilla--also located downtown, but much more casual. Great mexican food--hand made corn tortillas, fresh salsa/guac, amazing pork tacos. Not to be missed.
La Dolce Vita--italian (yes in Mexico) in the Hotel Zone. I didn't have high hopes and this place was recommended to my folks by a person they met at the pool. We are very italian and were impressed with homemade pastas--ravioli with veal (hard to find), etc.