I meet my sister here for lunch sometimes, one of the reasons is simply because they have their own parking lot!
The food isn't the best Mexican I have ever had, but it is pretty decent. The service at lunch is always really efficient, they get you in and fed in about 30 minutes...perfect for lunch! They give you two different salsas, and neither are for the faint of heart, both pack quite a bit of heat.
They usually have 3 lunch specials, which run around $7. They do a good job with their version of Green Chile Beef and the beans are pretty good.
Overall, a good place when trying to meet someone downtown...consistent food and easy, free parking!