I've been here twice now, and both times I had the cheeseburger. They were quite different (but both yummy) because there's tons of different topping options, some included with the price of the burger and a few premium items they charge extra for.
They (awesomely) make the burger patties with meat that's free of hormones and antibiotics. They pretty much let the meat stand on its own -- I would prefer a more seasoned patty personally, but I know many others who would disagree. They are big, sloppy, greasy burgers, in a good way. A single cheeseburger comes in at under $10, and it's a filling lunch by itself.
The place is small, but they have a decent number of seats and the decor is really charming -- classic Coca-Cola diner retro. The service is friendly, you get the feeling the staff is enjoying themselves and that's always nice.