Went to Mezcal for the first time yesterday and was pleasantly surprised! Had the spinach and chicken burrito which was delicious!! Pretty garlic-ly, so non-garlic fans beware. The burrito itself was HUGE, really huge. My one complaint was the salsa, not all that tasty - kind of like the stuff you can get at Tesco - and nothing like the salsa at Banditos or at Cantina. My friend's cheese quesadilla was really good too -- tasted strongly like Hermelin, though it had several different cheeses in it. The wait staff was great, a really friendly young Czech guy, who patiently listened to our mediocre Czech and responded back to us in Czech rather than English, which is always appreciated.
Our daiquiris were pretty par-usual and so was the house wine. Nothing to write home about but exactly what you would expect.
For a mexican restaurant in prague, the food was good and well-priced for the amount you receive.
Vegetarians beware, most of the meals are for carnivores.