We had a great stay here at Heinz's place ! Heinz was always very responsive and the office nearby meant that we could have help on any issue. Although the area of the apartment is not the most exciting, and not very safe at night, it is very centrally located so we were able to have easy access to many other places in Berlin. The only issue would be the internet that was not very stable at times, and the one desk in the living room is definitely not enough for 5 people working. I would suggest adding some tables in the other rooms. Overall though it was a really lovely experience in Berlin !