Marcus' place has a terrific location in Mitte, very close to public transportation & easy walking distance to interesting places (Museum Island, the Bernauer Strasse monument of the wall, Friedrichstrasse, Alexanderplatz....) It's small (1 room + kitchen & bathroom) but not cramped, overlooking a quiet courtyard. Many little cafés & restaurants nearby. There's no elevator so you should be OK with going up 3 small flights of stairs; and mind the two steps down when you go out the door of the apartment to the hall! Communication was easy, no problem at all getting the key. It was a very reasonable price for a great spot.