Overall we had a good stay at Georg's apartment. It looks exactly as advertised in the pictures (if not nicer). It is located in a nice neighborhood with lots of restaurant options near by, but also very close to a train station to explore Berlin. And since the apartment is located in the back, it is very quiet and peaceful.
Check-in was a little complicated and got re-scheduled twice. And I think it's worth mentioning that with people showering in a row, the water will turn cold after the 3rd person. We have been told from the host that there should be 20 to 30 minutes in between everyone showering, which was not possible for us since we all had to get to a conference in the morning.
Other than that, we had a good time!