Nic was just awesome. He is very nice and makes you feel very comfortable from the beginning. He was always happy to advise regarding activities to do and checked from time to time if we need anything.
The apartment was 100% as described (even better). We were 4 people (2 adults and 2 teenagers) and we felt completely comfortable in it. It is also very well decorated and that makes it even more fun.
The neighborhood has everything you may need at walking distance. Full of shops, groceries stores (supermarkets, 24/7), take away, restaurants, etc. The best thing is the tram which takes you everywhere in a few minutes.
The apartment and the building are extremely quiet. At some point, we suspected we are the only inhabitants of the zone.
I would not hesitate for a second to rent this apartment again next time in Berlin.