Dos is pretty good, as far as cheap Mexican food goes. It's certainly heads-and-shoulders over La Bamba, which is possibly the most disgusting place I've ever eaten, but that's not saying a whole lot.
I actually go to Dos fairly frequently, because it's close, it's cheap, and at the end of the day, it's pretty solid. Yeah, I pay for it a couple hours later, but that's most Mexican food for you.
The chips and salsa are good, nothing special. They serve two kinds: one that has chopped vegetables in it, and the other that's like a paste. If you ask, they'll just refill whichever one you prefer.
The menu is decent, except almost everything comes absolutely smothered in cheese sauce. Some people love it, but I get sick of it. Make sure you get beans: for whatever reason, they're tasty here, and I *hate* beans.
All-in-all, not pricey, decent food, and usually pretty quick service. If you're staying around campus, this is a good place to eat.