We stayed 2 nights in Daniel's apartment. It is on the 4th floor (there is a lift!) and is very clean and exactly as described.
The apartment is a 5 min walk from Bellevue S-bahn station which is 2 mins by train to Berlin Hbf - so location is excellent.
It is also very quiet which is a bonus!
Daniel met us and made us feel very welcome; he showed us round the apartment and gave us information about access to the train station.
We found a wonderful little cafe just 1 min walk away - on Melanchthonstraße - well worth a visit or two!