Johann is a very cool, easy-going guy, with whom you can discuss a lot of different things. He has a wide array of knowledge and he is also very polite. He knows Berlin like the palm of his hand and he can give a lot of "inside" tips for the city. The apartment is very artistic, cozy and gives you "warm" feelings by the time you step your foot inside it. I stayed there for 4 months for my PhD research and everything was great. The building is located in a very quiet, green, family-type area and the metro station (U-Bahn) is only 4 minutes away. I already miss everything!