Our trip in Berlin was fantastic. The flat is better than a room in a hotel ! Everything is organized and clean and you can feel like home in that flat.
Anna was really adaptable and helpful. I would definitly recommand that place for a couple or some friends.
The only thing is that the location is a bit further than we thought (you need to take a metro for 4 stops to reach the center alexanderplatz) but don't worry, the area is absolutly charming to take a brunch on sundays !