I've ordered takeout from Mexican Amigos several times since they've opened, usually tacos or burritos. I can't speak to the dine-in experience, but the takeout service has always been friendly and efficient.
The food is standard Mexican fare; burritos are perhaps slightly more authentic than the mission style burritos found at Burrito Boyz and the like. I've only ever had their ground beef tacos and burritos; beware: the last few bites will be wet with a combination of juice and grease from the meat. Excessive moisture aside, the beef was nicely seasoned, though not mindblowingly delicious. Worth the $6 for a small (which is still a decent size).
One thing standing in the way of Mexican Amigos' success seems to be the management. The woman who handles the takeout counter usually does a great job, but there was one day that I was there and she had a ton of orders coming in with no help from any other staff. It took over 20 minutes to get one burrito, and I contacted management to suggest training other staff to help out during busy times. I got a prompt response thanking me for my concern, and an offer of 50% off my next order.
The next time I went in, I was cornered by the manager, who wanted to know who had served me that day. He spoke over me as I tried to reiterate that I didn't think the fault was with the takeout staff, and just kept repeating that his standard is 3 - 5 minutes to prepare and serve a burrito (way too fast, in my opinion; I'd like all my fillings heated through properly). I came away from that conversation feeling like he took zero responsibility for the incident and was more concerned with blaming his staff. I ended up talking to the staff member in question separately to stress that I was not unhappy with her, but with the understaffing of the takeout area.
Based on the ratings from other Yelp users, I'd recommend sticking to takeout only; even on a busy day, the service seems to be better than in the restaurant.