I have been at Jan place for 7 weeks and I really would not recommend this place for several reasons:
1. There were building restoring works for almost all my staying which were really annoying for the noise and the dirtiness. The owner never mentioned this fact before my arrival and this was really annoying especially for a student in Berlin to prepare his exams.
2. The owner is really stingy, especially with the heating. A lot of times he came to my room (where the heating controller is) to turn it down without telling it in advance or asking your opinion about it. This is very annoying especially in the freezing berlin winters.
3. The room is described and priced as a luxury room in Prenzlauer Berg but It is not. The room is located in another district: Pankow and to reach the hearth of Prenzlauer berg It takes almost half an hour by foot. In Prenzlauer berg you can find better alternatives at lower prices but It was my first time in Berlin so I did not know it.
4. Personally, I found Jan not really talkative especially regarding the explanations of domestic issues.
I have been flatsharing and living alone for three years and I am a really easy going and friendly person and this was my first time bad experience.
In conclusion, I would not really advice this place, especially for long staying.