What a LOVELY flat! Great location, beautifully decorated, nice and clean and tidy, and well equipped with everything you need. The only downside of the flat is that there are a lot of stairs to climb (Jon warned me about this in advance though, which was nice of him) and there is a little bit of traffic noise in two of the bedrooms. But having said that, we didn't find it too much of a problem and would 100% return!
Thanks Jon for a wonderful stay in a great part of Berlin.