We had a wonderful time staying at Lena's apartment. We espacially loved the big living room and the nice balcony. Also the location is great: Kreuzberg is a nice place. We rented during our whole stay bikes and places like Friedrichshain (10 min by bike) Prenzlauer berg (a bit over 20 min by bike) and the centre (a bit over 10 min) where really easy to go to.