Cornelius' apartment was everything the lovely pictures promised, and more. We were first met in the apartment by Linda, who was very friendly, and thorough in her apartment guiding.
My mom ,sister, and I were in Berlin for almost a week, and we needed a place that accommodated 3 people easily, close to local transportation, interesting restaurants, and in a charming neighbourhood...and we found all of these things at Cornelius' place. We all enjoyed sitting outside on the super cute balcony, with a roof top view. I slept on the sofa bed, and it was one of the more comfortable pullout couches I've slept on.
The apartment is very close to the tram and the S-bahn, which gives you easy access to the rest of Berlin, but I do recommend exploring Prenzlauer Berg as much as you can. It is such a nice area!
Would definitely stay at this place again.