Wolfram and his wife were very kind and helpful. The apartment is well located, just a few steps from the Möckernbrücke U-bahn station and 10 minutes by foot from the heart of kreuzberg. It is also surrounded by great cafes and restaurants,
However the apartment itself is really small. We were four and we spent an entire week there and it was way too small. Moreover, since the shower and the toilet are located in the middle of the apartment, there is no way to have some kind of privacy.
I would recommend this apartment to a couple or a group staying in Berlin for a few nights and who doesn't wish to spend a lot of time in the apartment.