My stay at Kilian's was great. He's a good host, can give you information about the city and is just a cool guy.
The apartment is spacious and very centrally located. A lot of attractions like the Wall Memorial, "Unter den Linden", Brandenburg Gate can be reached by foot (the latter is a bit of a walk, but I love walking!). The near surroundings offer a lot of nice restauration. Swimming pool across the street. More about the apartment: Well-equipped kitchen, comfy bedding, ...
I hope to come back to Berlin and stay with Kilian again!