We stayed four nights in the flat of Cornelius. We had a very wonderful experience. The apartment was great and had everything you could need. The location was also ideal with train and tram stations very close and a short walk to many shops and restaurants. Cornelius was a great host. All communication was easy and he was understanding and helpful when we had to change our arrival times due to a train cancellation. Overall I would strongly recommend this stay for anybody and will definitely stay there again myself when I am next in Berlin.