We absolutely loved staying at Marko's place. He was very communicative and made check-in extremely easy by meeting us at the apartment with keys. When we got there, the kitchen was stocked with fresh bread from a local bakery (which was so good, we returned daily!), coffee, tea, beer, chocolate and milk.
The apartment itself is incredibly well decorated - we felt like we were staying in an art museum. We were three people, and the space was great for us. There is one bed that comfortably fits two, and an air bed for one. There is also a couch if everyone prefers to have their own space. It also had everything we needed in terms of amenities.
The neighborhood is lovely - about 7 minutes walk from the S-bahn and 10 minutes to the U-bahn. There are great local restaurants and cafe/bars to hang out it, and it's very close to the center of Neuköln and just south of Kreuzberg, where some of the City's best restaurants now reside. Marko left us a couple of great guide books, but he also pointed out his top recommendations in the area.
I would highly recommend Marko's place - we will definitely seek it out next time we're in Berlin!