We had an absolutely fantastic time in Berlin. This apartment was in the perfect location. It feels like being in a lovely old village, with quaint little public squares and plenty of charming and inexpensive restaurants and cafes, but the s-bahn and u-bahn stations are just a short walk away, so you can be in any part of the city within minutes. It is a also a short walk to the Estrel Convention centre, so it's perfect for folks attending events there.
The apartment itself is high up, which means plenty of stairs, but they were worth it for the view of sky and treetops. The windows let in lots of light, and there is even a balcony to enjoy if you travel at a warmer time of year (i.e. not October!) Apart from being beautiful and spacious, it was quiet, warm and comfortable. It really is as nice as it looks in the photographs.
Thanks Marlon!