Been a few times and based on my experience you're safest sticking with chili and tea or beer. The other dishes I have had ranged from OK to pretty poor. For example, the spaghetti was quite soggy, the sauce was very bland and the overall taste and texture wasn't much better than opening a can of tomato sauce and pouring it over well cooked noodles. However, the chili has been consistently good.
Service can be pretty slow, particularly at busy times. At lunch prepare for a long wait even to order. And an even longer wait to get your food. The staff can vary from looking and acting like they just got out on work release to being pleasant and helpful. Usually I find them to be on the less friendly and helpful side.
In short, I'm not a professional chef but I can slay their cooking in most dishes. Portions are slim (chili) to moderate (except for nachos) so don't come too hungry. And plan for a real dive atmosphere with service to match.