My family and I had the most wonderfull time in Berlin, and a great part of it was because of our fantastic accomodation in Kathrin's apartment!
The apartment was even greater than what we had expected from the pictures - they do not fully do it justice!
It was large, bright, quiet, and well kept! The only small minus was that there wasn't any door for one of the rooms, but only some fabrick to close of with.
All in all we will fully recomend the apartment which, furthermore, has a great location near to the u-bahn, and a great Italian restaurante just across the street ;)