Do not let the look of the building turn you away, the food here is amazing. Food is always amazingly flavorful, and fresh tasting. The staff are very polite, are willing to take special requests that aren't on the menu and make excellent recommendations.
The carne asada burrito is my favorite thing on the menu. The meat is spiced, marinated and grilled on site. It comes with guacamole and pico de gallo, I usually just get it with the pico (not a huge fan of avocados) - tastes amazing! They have a fresh salsa bar with lots of toppings you can add to the burrito or what ever you decide to order - the smokey red salsa is incredible.
People I've taken tree have also loved the el pastor tacos, breakfast burritos, and many other items.