I've eaten at Paco's a bunch of times for lunch over the past four years. My employer's regional office is in South Park, so this is one of a handful of restaurants my co-workers frequent when we're in town for a meeting or training. I've never been here for dinner, but I highly recommend Paco's for a tasty and hearty lunch.
I typically get the tacos- they have several different combos that are good. Brisket, fish or shrimp, skirt steak, and gringo beef are all good. The sides of rice and refried or black beans are a good compliment. My favorite other than the tacos is the "bacon egg and cheese" enchilada. It has jalapeƱo bacon with a chili/gravy and a fried egg on top. Not the healthiest thing in the world, but so tasty!
Service is typically good. It can get slow during busy times like many other places, but I don't remember any issues. I can eat here once a month or more and still keep coming back.