Taqueria el Mariachi in Waltham has changed their name, but I don't know if it has changed ownership.
Finally got around to checking this place out for lunch today after reading positive posts here about the place. Had the burrito combo (burrito and taco)with carne asada in the burrito and tacos al pastor in the taco. Taco was ok with sizeable amount of small bits of pork sauteed in a chili sauce topped with a wee bit of lettuce, tomato, and onion wrapped in two warm corn tortillas. The burrito was lacking in flavor with small bits of steak that was sauteed and not seared which made it almost flavorless. Also stuffed in there was bland refried beans, lettuce, tomato, onion, and a bit of creme. I spruced it up a bit with the decent pico de gallo that was served with a basket of chips.
Saw someone get a shrimp plate that looked good with grilled shrimp, refried beans, and white rice. This was not listed on the menu, so I guess you gotta know to get it?
Tried to get a Cabeza (beef cheek) taco, but they did not have Cabeza - still on the menu though so they may have just been out of it. The menu has not changed since the name change since you can see that they just wrote in Amigo where Mariachi used to be on the takeout menu.
Not really impressed with this place even though everyone was really friendly and I did not feel out of place even tough I was the only gringo in the joint. I will try one more time to try the beef cheeks and/or one of the plates.