They recommend you visit their website and make a reservation.
That said this was a charming place to go for dinner. Great, friendly staff took really great care of us. I was surprised at how family friendly the place was. While we were there I saw many children sort of wondering around and generally having a great time.
This was my first go at having German food, so I honestly can't speak to how authentic it was but everything served was wonderful, from the starter bread and salad to the main course to the dessert. (yes... really... do save room for the dessert. Totally worth it.)