Ralph responded to every question I had and even provided us with an extra mattress for a friend who came over for a few days. His partner welcomed us to the apartment. They also gave us some good tips to visit in the neighborhood, enjoyed that!
The place is very clean, with lots of vintage stuff and a wooden floor. The kitchen has everything you need, the most things are brand new, so you can cook at home. A bottle of red wine was waiting for us in the kitchen!
There are a lot of nice bars in the neighborhood, the apartment is also good situated to visit the other areas in Berlin. We hired bikes (Rent a Bike at Mariannenstrasse is very good!), that's a must if you want to visit Berlin!
Görlitzer Park is right in front of the apartment, it's a nice hangout spot where you can enjoy drinks, various people who are busking, bbq'ing, enjoying the sun..
Would definitely recommend Ralph's place!