We would definitely recommend Vincent's place. It's situated in one of the best locations of Berlin (my favorite) and the room is very spacious, having a mix of living-room and bedroom for a very good price. The flat is suited best for young people or used travellers instead of families for example, as it has a "student young life" vibe to it. Communication with Vincent was very easy and he was always very reliable. It's a 4th floor with no elevator, important notice if carrying luggage.
Thanks Vincent for your hospitality and I hope we did well as guests!