This place opened on Beacon relatively recently, I believe (there're a number of posts about the Waltham location). I feel I've lost my ability to rate Mexican food on an absolute scale, but on a relative Boston scale it seems quite good. It appears to use all the right ingredients (unlike, say, El Pelon), none of that horribly greasy taste you get in local "mexican" chains, and I enjoyed two meals from there in two days with no regrets. At any rate, I'll stick to the details, and others can evaluate the quality for themselves.
Meal 1: steak, chicken, and tongue tacos, steak torta. beef seemed a bit over-salted/seasoned, but pretty tender. as if to compensate, chicken had almost no flavoring at all (no signs even of being grilled), so it was the weakest of the dishes. tongue was very simple and delicious in its simplicity - just boiled tongue, mmmm... the torta came on long (as opposed to round) bread (which surprised me a little, but perhaps that's as common), but the bread was in fact good. the goopy mess that was inside the bread was tasty, the overseasoned meat aside.
Meal 2: chilaquiles, huevoes rancheros with refried beans and potatoes, beef and potato tostada. chilaquiles had a very nice green salsa and a bit too much cheese for my taste (but that might be just me). they also came with somehow extra-tasty fried onions and peppers and good rice (i know that should be a given, but it really isn't sometimes). rancheros made for a fantastic breakfast-style meal - eggs fried exactly right, decent beans, great home-style fried potatoes. mix it all up and get to work. the tostada was fine - same potatoes, strongly seasoned ground meat.
Overall, definitely deserving of repeat business, IMHO.