I've been going to La Milpa for years, and love this place. The con above is a double edged sword; busy is good for the restaurant, but sometimes the service suffers if the wait staff has too many to serve. The food, though, always is good, no matter how busy. It is always fresh and piping hot, and most importantly great tasting. I've been to most of the Mexican places in the area, and this is one of the best.
Pros: Fast, friendly service
Cons: Can get busy on weekends, so go early