I stayed at Ben's apartment for two months (did an internship in Berlin) and my girlfriend stayed for the first month as well. We can highly recommend it to you. The flat is not only located at a great place from where you can explore Berlin conveniently, but is also exceptionally clean and you will enjoy great comfort with regard to various aspects. Ben himself is a very friendly person and we had nice conversations. He helped us whenever we needed something and proactively organized a very pleasant stay for us.