We had an excellent stay in Stamatis' place a month in July-August! The flat is charming and bigger than it looks from the pictures. The location of the place superb: close to great restaurants, bars, cafés and shops, but on a quiet street.
Stamatis was a good host and communication was quick and easy. Check-in and check-out worked great, and he sent us a message a few days after we had arrived to make sure everything was working, which we thought was a nice thing to do.
Highly recommened for a nice stay in Berlin!