My boyfriend and I spent 3 nights in Sara's apartment and it was great. Her place is located near the S-Bahn station (aprox 3 minutes) and 15 minutes from the old center. The neighbourhood is quiet, with lots of coffee shops, restaurants and supermarkets. The place was clean and had all the things that we needed. Sara and Jan are really good hosts, they're very open and understanding (we landed in Berlin kind of late and Jan waited for us to hand over the keys and to give us some tips about the neighbourhood). They responded quickly and were hospitable. We totally recommend this place!