Stefan is a very kindly host, always available for us. The apartment couldn't be better; it's the firt time for me that a location is much better in person that it's photos. It's located in one of the best parts of Berlin, plenty of cafes, bars and a lot of cool ambient. You've got many transportation in a few meters around, so it very easy go to anyplaces.
The apartment itself is very luminous and has a nice balcony to the park. Comfortable beds, full kitchen and all you need to stay comfortably in Berlin. We are a family of 3 and stayed for 10 days, but we could stay happily for months.