We had a nice stay at Rainer's place. He was not able to meet us, but was able to make the check-in process painless anyway.
He has a beautiful flat, and it is fairly close to the metro, so it was easy to get around.
The neighborhood was lively, especially on the Friday night we were there, but it was still surprisingly quiet in our room.
The only issue we experienced was a loose door handle on the door into the rest if the flat. Also, if you don't like stairs, this may not be the place for you, as it's up ~7 flights of stairs. Otherwise, everything went well during our stay with Rainer.