Starting from the "building" itself, you will enjoy the entrance/front part, which appears to have…read morelanded here straight from an American movie :) Inside also, the decoration is in pure American 50s/60s diner style. Very nice indeed.
Moving to the food side of things, there menu offers everything you would expect: Burgers (regular beef, American Angus beef, chicken), pulled pork, hot dogs and chilli, and of course milk shakes. There's also a few expected salads and appetizers. Sadly, steaks are missing.
We ordered several different burgers, and everyone left happy. Mine was the Farmer's, with bacon and an omelette, which was a nice difference compared to the usual fried egg.
Prices are neither low nor high considering the style of the restaurant and the cost of similar joints. Overall, I would say a recommended choice for American dining in Karlsruhe.