We spent a week in Katrin's flat and it was great !
We came in family with our two little daughters and there was everything we need to be relax during our stay there. The flat has been well conceived with a ground floor made for living with access to a terrace and a shared private garden. The first floor is made for night time. Katrin was very kind and quick to answer my questions before and after making the reservation. The neighbors are also very kind and welcoming. There are several bus lines in the streets near Katrin's place.
Well I can just recommend this place for a relax and confortable stay in Berlin !