We had a very nice time at Andres' flat. Andres was there when we arrived at the flat from Schönefeld airport and told us everything we needed to know about the flat and the area. It's very close to many bars and restaurants in the Neukölln ; about 5mns walk from Hermannplatz station.
Andres made a list of places of interests around his flat, he also had extra beds and covers if you didn't want to share a bed!
I would recommend this place if you want to stay in a more laid back area of Berlin and be able to walk to cheaper bars and restaurants. Still, it is quick and easy to get to the more touristic areas.