Having recently stayed with my mother in Stefan's apartment in December, we can certainly recommend it. The location is great, being less than 5 minutes to the nearest U Bahn (Senefelderplatz) and Kollwitzkiez is a nice area conveniently situated between Mitte and Prenzlauer Berg. Martina met us on arrival to show us around the apartment. Communication, checkin and checkout were straight forward and we appreciated the flexibility to our travel schedule. The apartment is well designed, warm, with good ammenity and generally quiet. We did experience some noise from the apartment upstairs and stairwell due to a young child running around, but it didn't impact our stay. As it was winter we couldn't utilise the amazing private courtyard to the fullest, but the sauna was great! Thanks again for having us.