My girlfriend and I stopped by Fat Head's for lunch on a Sunday. It was fairly crowded and we were seated at a table upstairs. The menu is full of sandwiches, burgers, other bar-type food, and headwiches (sandwiches the size of your head). We both decided on burgers. I ordered the smoky burger and she ordered the gluten free triple bypass burger (and substituted the beasty BBQ sauce for the smoky BBQ sauce). Both burgers were juicy and flavorful, and the fries they were served with were solid. We were both pleasantly surprised by the gluten free bun. The portions were very generous. We couldn't finish and had to take the remains to go. Our waitress was friendly and the service wasn't too slow.
I'd definitely go back, but I'd probably have to prepare my stomach ahead of time. If you plan on going to Fat Head's (which you should), bring an appetite.