Christoph's place looks exactly as in the pictures. The apartment is really nice and when we arrived it was in a very good shape (tidy, clean bedsheets, clean bathroom and kitchen). The kitchen is fully equipped and the bathroom as well (with a laundry machine and a dryer). The heating works perfectly and it was always warm.
The location of the apartment is not ideal. It's either a 35' walk to the city center or a 20' metro ride (which is not very cheap). However, the neighbourhood is very nice and there are a few supermarkets and restaurants around.
The only thing that didn't go as expected was that the day of our arrival we had to get the keys from a shop near the building and Christoph hadn't given us the floor and the apartment number. So we arrived having the keys but without knowing where to go. He wasn't replying to the messages and thanks to the kind tenants of the building that were very willing to help us and that they called him we managed to get inside the flat after ~1h