I stayed as a guest of Annika at this flat for approximately seven weeks contiguously in late 2012. I really enjoyed the flat. You couldn't ask for a better location. It's away from the bustle of downtown, but a five-minute, one-stop ride on the S-Bahn gets you to the Hauptbahnhof! 1.6 EUR and five minutes and you're at the transport hub of the city. I was enormously delighted to discover Tiergarten park, about a 5 minute walk away. It's like the Central Park of Berlin. A 30-minute walk through the park will take you all the way to the Brandenburger Tor and the Reichstag. The river Spree is 100m away and there are scenic walkways on either shore that you can take all the way into the city center, very beautiful. For food & drink staples there's a Rewe and a Getränke Hoffmann right nearby - easy walking distance. Cafes and take-out food are a few minutes away on foot under the Bellevue S-Bahn stop.
I didn't meet Annika, but her property manager Johannes did his job superbly. His English is first-class and I think I learned more about Berlin and German history and culture from talking to him than I did anywhere else in DE. The flat is extremely quiet - so much so that I wondered sometimes if I had any neighbors at all! The eighth-floor location is far above traffic noise and provides for a scenic view of the horizon to the west as well as to the riverfront. I have many memorable photos from that balcony. The pigeons are your friends! The kitchen is adequate, though not equipped for much more than basic cooking. There is a microwave and a wonderful tiny clothes washer. The Wi-fi service is adequate. A wealth of cleaning supplies are provided for the long-term guest. Clothing storage, while not expansive, is likely adequate for most singles or couples. I have fond memories of my time staying at this flat and would happily do so again.