I booked the room for my mum. It was a generally very positive experience. Fabian was totally unproblematic when the train was running late and left the keys for us to pick up just next door with instructions on how to get in. In general, communication with him was without problems. We didn't get to meet him, my mum only met a friend of his who came by to check everything was running smoothly. This resulted in perhaps the only point some people could mind, as she left the washing machine run overnight, but it's located in the bathroom and my mum didn't really mind it. Otherwise the place is as advertised - quiet, clean and fully functional for a few days stopover, and on one of the best location in Berlin for mainstream visitors. Recommendable.