Our stay in Wolfram's appartement was fantastic: it is quiet, charming, and perfectly located to discover Berlin. Wolfram was very helpful and welcomed us as friends.
There are public transports (U-bahn and bus), shops (including an excellent French café) and restaurants next door.
The appartment is well equipped, especially the kitchen. The terrace is lovely.
There is no washing machine but there is a laundry within a 10 mn walk. The wifi is a little bit unstable and all the sleeping places are on sofas.
We highly recommend this place.