They have a variety of foods you can buy that are fully cooked and not cooked. Today I had the chile relleno and bean/rice/cheese burrito and it was delicious. In the past I have had their carne asada and it was also delicious. My roommate stopped by one evening and ordered the uncooked chicken that was so good it was very tender and the way it was prepared by the carniceria was perfect.
They also have pan dulce (sweet bread) and little things you may need here and there without having to go through the hassle of going to your grocery store.
One important thing to note is the staff is very nice and friendly always smiling.