The title says it all. Gregor's apartment is truly a small paradise in Berlin. We were 3 guys 19yrs and we stayed for 7 night in August 2013. The Apartment was spacious enough for the three of us. The double bed and futon were very comfortable, while the single size bed is a little uncomfortable but bearable. The complex itself is beautiful and very quiet.
The biggest advantage is the location. The apartment is located in a nice closed residential complex in the middle of quiet Kreuzberg and is nearby 2 U-bahn stations served by 2 lines that can get you almost anywhere you want in berlin in less than 10 mins.

I must say that the apartment was a bit dirty although the cleaning lady was cleaning exactly when we arrived.
Thank you Gregor!