I really hoped this place would be better.
My biggest gripe is the food--everything else I can forgive. All burgers are served the same temp (well), which means the meat is frozen. For the price, I would expect more. That said, my mushroom swiss burger was good. The AZ smashburger had too much going on--a lot of conflicting flavors that didn't make a cohesive burger.
Fries: Smashfries: yum. Veg Frites: pass. They truly are still vegetables and taste like it.
Okay, and all the rest...
Service: an inefficient model. None of the workers seemed to have assigned posts, and milled around aimlessly. This probably caused the dirty seats. Milkshake delivery was similarly inefficient, tying up the people assigned to the cashier's desk until they finished blending the shakes. I would fix this, especially for busy high-peak times.
Practical advice: bring a sweater! there was quite a wind-tunnel in the place.