We had a great time in Berlin and Sara's place was in a perfect location for our family adventures. As other reviewers have noted, the flat is very near the S-bahn so you will hear the sound of trains going by. On the plus side, this made getting to/from the airport very easy. The flat was clean and decent, nothing fancy but very suitable for a family holiday in the city. We spent a lot of our time at Helmholtz plate playground and drinking coffee at St Oberholz.