Christoph had wonderful communication from the moment we asked to book our stay. He was really flexible with check in and check out which was really helpful for us! The flat isn't located in the centre of Berlin but the super cool area of Kreuzberg. There are loads of cafes, restaurants and bars nearby - you'll be spoiled for choice but make sure to check out the Street Food Thursdays at Markthalle Neun! Plenty of transport links to get anywhere you need to go.
The flat itself is even better than in the photos. Really modern with great artwork by Christoph himself, nice touch! There are two balconies which was wonderful for relaxing after a long day of sightseeing. Really clean, TV and sound system (which we didn't end up using but there if you want), good WiFi and well equipped bathroom (shower and bath) and kitchen.
Be warned the flat is on the 7th floor and there is no elevator - we knew this before booking from Reading previous reviews :) Only negative thing we have to say is we could have done with a couple more towels but we managed just fine!
Thanks so much for letting us stay, we can't wait to visit Berlin again!! :)