We stayed in the apartment in early February. The neighbourhood is quiet, family-friendly with lots of places to eat (check out Heuberger, if you are there) and several bus stops and railways stations to choose from depending on where you are headed. The place is easy to find and the apartment building is very nice. No elevator, though, and the apartment is on the top floor, so it's a long way up.
The apartment is well-equipped, clean and bright. We got everything we needed for a comfortable stay. Great TV, fast Wi-Fi, nice bathroom, big kitchen and a large bed.
Though the terrace was still being renovated during our stay, we didn't need it as the weather wasn't that welcoming.
Carsten was very helpful and answered all our questions quite quickly.
All in all, everything was great and we highly recommend Carsten's apartment.