I'm always excited about a new Mexican or burrito joint in town. I welcome the addition of GSB. My first impression is that it's a clean, friendly addition to the Madison burrito sweepstakes. The service and venue are great; the food, barely OK.
I ordered the chicken burrito and it was well-assembled with pico and chicken, minus the bean and rice fillers that most of us can do without and that I, in fact, usually omit when going to Chipotle or Qdoba or other burrito joints.
The veggies and salsa were great -- they seemed fresh and had a nice kick. The chicken, however, tasted heavily salty and didn't appear to be the quality cuts of white meat that I would hope for. It reminded me less of Chipotle and more of Taco Bell.
My suggestion for more stars would be to upgrade the chicken, but since GSB is a chain, this might be difficult to do. Don't try to hide lower-quality meat by salting. This might fool the 2:30 a.m. bar-time crowd, but not many others. While I'm not ruling out trying them again, I will pass on anything containing chicken.