I had a really wonderful time at Kristian and Peggy's apartment and 100% recommend it. The apartment design is stunning and you really cannot find a better location in Berlin. If you're looking for somewhere central, this is an incredible place to be.
Peggy and Kristian were very easy to communicate with and very helpful with anything I needed. They live in the building and have a studio there so there's always someone to help if you need anything. Jutte at the studio was really wonderful and she even looked after my shipping when I was out.
WiFi was great for those wanting to work from the apartment and the kitchen is also great for those staying longer. They just renovated so the place is pristine.
Highly recommend!