This place is more novelty than anything. It's about as aggressive 1930's American-themed as it…read moregets. It's in a cute little, well, railway diner-style compartment. The staff is so kind, with smiles all around.
The food, however, varies quite dramatically. The first thing to note is that the prices aren't too bad. You can get your fill for under €10 here. Their burgers and fries are delicious. The burgers especially are quite large. Their steaks are pretty disappointing, though. I asked for mine to be medium rare and it came out well done. The fat wasn't marbled and was just in one strip, even though I had ordered the ribeye (this was likely not a ribeye). The salad that I ordered was heavily DRENCHED in dressing and cheese, and there was little variety of greens and other assortments in it.
My friend had ordered the Mac-and-cheese, and it was hands down the worst we've ever had. It looked very liquid-y, much closer to a soup, which initially we assumed was cream and cheese, but upon eating it, we figured out it was actually WATERY. Germans apparently don't know how to make Mac-and-cheese. I've had better $1 instant mac-and-cheeses.
The waitress, though, noticed we didn't like it and ended up not charging us for it. Seriously, cannot stress how kind the wait staff is.
I'd still definitely come back. Though the food varies and can be mediocre, it's often pretty good, and the experience is well worth it.