We've had a perfect stay in Jan's place. Jan was very responsive before our arrival, welcomed us personally and was very keen on giving any touristy assistance we might have required.
The flat was big, absolutely impeccable, freshly cleaned and the beds were comfortable. The neighbourhood is really quiet and safe. We rented bicycles during our stay and had no problem leaving them outside overnight. Jan had left some lovely attentions for us, which was very kind.
We will definitely stay again if we return to Berlin!