Sebastian's flat is fabulous! He describes it correctly in saying that it is "cozy" but it was actually much roomier than I anticipated. It fit our family of four (two adult son's perfectly). The location is superb as it is very close to the airport and U stations. The neighborhood is great with many eateries, grocery stores etc all within walking distance.
As a host Sebastian went above and beyond my expectations. He answered all of my questions quickly and accurately (even the silly/weird questions I had). I feel I made a friend with our correspondence.
The bottom line is if I am ever fortunate to go back to Berlin this is where I will stay.