The guy working there was very friendly, and that alone makes me hesitate to give a poor review.
I love the concept. The inclusion of gluten-free buns is great (though holy crap at the $3 upcharge).
The fries were tasty, but the burgers didn't live up to the descriptions nor the photos of the options on the wall (which showed 1/3 or 1/2 pound burgers). The size of the actual patties made McDonald's burgers look generous. The enormity of the gf buns wasn't helpful; they dwarfed the toppings and meat.
We felt really 'meh,' which made me sad and made me sorry to part with $30 for two gf burgers, one order of fries, and one bottle of water.
They could learn a lot from Roam Burger in San Francisco, which has a similar concept with excellent execution.