I have been to many Mexican restaurants in Nashville, and this is by far the closest to actual Mexican/Central American dining I've found so far. The burrito Las Americas is the best burrito in town (and at $3.99, possibly the cheapest). The tacos are authentic, fresh and delicious. And the specialty item, the pupusa, is fantastic. Service is always good, even if communication is occasionally difficult. Don't let the bars on the windows and somewhat trashy-looking exterior keep you from discovering one of Nashville's best-kept secrets.
Pros: wonderful food, even better prices
Cons: sometimes crowded, only average atmosphere