This is THE place to go if you're on the East side of the square at bar time and you're hungry. The food is very good, it's cheap, and they're open very late.
Don't go here if you've only got 20 minutes--you'll be waiting a while for the food. But the staff are great, and as I said, the food's even better. So far, I haven't found a better spot for mole in Madison. Also? The portions are pretty huge.
Sometimes it can get pretty loud (well duh--it's a restaurant that caters to the late-night crowd). Someday I'll have to try it during regular hours...