They have moved (as of early February 2013) and are now at: 1106 W University Ave
Urbana, IL 61801 (217) 344-6711
Haven't tried them at the new location, but perfectly fine Mexican food when I went there several times at the Springfield Ave restaurant. Very reasonable prices and pleasant staff, good chips and rice and beans. I've had the tamales, tacos and enchiladas, and they're just how Americans like them :) There are other more authentic places I suppose, but there's room in C/U for a place like Mas Amigos too.