We liked very much the Cornelius apartment. It's close to the S-Bahn station, two markets (a bio one and a conventional one), and a lot of restaurants. The apartment has a clean decoration, ad have a lot of beautiful lights (you can choose what kind of lights you will turn on). The kitchen has everything you need, and you have a big privacy there. The bathroom floor is heated (no more problems to go there on the winter!) and the shower is excelent.
So, I recommend this place! We felt like a real berliner there!