I went to Amsterdam with a friend and the stay was great. The flat is even better than in pics (a bit dangerous stairs, but the rest is great). The neighborhood is really calm and well connected to city center by tram (15-20min) and night bus (20-25min).
Piet is a really nice and good host. He gave us all details to get to the flat without any problem and helped us with maps and turistic info (he has all brochures prepared for guests).
I would really recommed this place to stay :)