I don't understand the bad reviews. Most of the food is tasty and I really enjoy eating here.
The mixed enchilada plate is great, as is the cochinita pibil. Salsas and guac are great. The tacos are pretty good but I would say not their strong suit -- for that, there are better taco places in the city. Service has generally been fine whenever I've been there.
Overall I like the food & ambience, and I think this is a solid choice for good Mexican.