Jürgen was a bit slow to respond when we first made our booking, but he was probably busy as he had a few apartments in the same building with many check-ins to deal with daily! He was communicative when we needed him to be, which is all we needed. He has all the information you need (where to clear trash, wifi password, etc) on a board in the room so it's all fuss-free.
The room was wonderful space, and the pictures don't do it any justice. It was bigger than it looks. The room has everything you need and more. The best parts of the room include strong water pressure, heater in the bathroom (a god-sent when it's cold during winter and you don't shiver from the cold after a shower), high speed and reliable wifi. It was a short 4 min walk from the nearest metro. My only minor comment would be that the bedside tables were a bit dusty, but we wiped it down ourselves and the rest of the room was very clean. Overall a very lovely and comfortable stay!