We had a very nice stay in Crystal's apartment.
Upon arrival Crystal provided us with chocolate, nuts, cookies, several bath products and several maps of Berlin. We got also introduced to the house cat Mofo who's adorable.
Despite no curtains in front of the windows we could sleep very well.
Location is very good as it is just about 100 meters away from the S-Bahn and U-Bahn Station.
Based on our experiences we would say: Recommended.