I just returned from a 1 week trip---had a couple good meals.
The highlight was: Los Tres Gallos---on Leona Vicaro at 20 de Noviembre. Several small tables with candles, burlap placemats, terra cotta plates---nice amenities for a small informal place. No real menu, but the very welcoming staff tells you what tacos, quesadillas, and other options are available. We tried the chicharron, huitlacoche, and pollo tacos--the chile relleno and the chicken mole. All were outstanding. The tortillas are hand made and grilled on a griddle just outside. The mole is a home recipe---7 different chiles, apple, chocolate...and lots of other ingredients. They don't sell beer, but can get some from a nearby store if you ask. Coming from San Francisco, where I eat a lot of great Mexican food, this place was a real treat.
I had a decent meal at 12 Tribes in the Casa Dorado hotel. Nice atmosphere, a little ambitious menu but pretty nicely done. Not sure I'd do the "International" items, but what I had was interesting and well prepared.
The seafood taco place on Leona Vicario a few blocks into town (its a fenced in space with corrugated tin roof) was OK---pulpo tacos were great, smoked marlin was good, the scallop tacos were a little iffy.
Marty's La Ricazon---Food was OK. Seems like a strange combination of Mexican and American influences. The jicama salad was ovewhelmed by the creamy dressing, the tacos were good but nothing special. Maybe I was expecting something terrific based on the TripAdvisor reviews, but I wasn't impressed.