We just finished a five night stay at Alexander's apartment and had a wonderful stay. Alexander was very responsive before our visit and gave us really good instructions from the train station to get to the apartment. He was waiting for us when we arrived (he was really considerate when we phoned when our train was late) and showed us the apartment. He has a very helpful map with restaurant and bar suggestions. The apartment was exactly as advertised and a great base for our stay in Berlin. The apartment is only minutes away from the M41 bus line (a great route that will get you to the train station as well as Potzdamer Platz) and the Kortbusser Tor U-Bahn station (U1 and U8 trains...we used this station a lot!). The apartment is in a great part of Berlin (not a far U-Bahn or bus ride to the major sites) with a lot of character, and the area is pretty quiet at night so you won't have to worry about loud noises keeping you up. Overall, I would recommend staying at Alexander's apartment when in Berlin.