We stayed there for three nights. Arnd was very nice to us and indicated how to get there from the airport, he also made sure we were ok during our stay. The room and bathroom were clean and tidy.
The only problems were the bad internet connection from the room and one night we had some mosquitoes around.
Nonetheless I would stay there again. Location is great: 20 minutes walk to Brandenburg Tower and 10 minutes to a train station aprox. The neighbourhood seemed nice and there was a supermarket right across the street.