I stayed in a single room. It was clean and comfortable.
The view of outside(like a garden) was not exactly same as the photo, but the room was not bad so it's fine. There's free wifi ID on each room. And the hotel gave me a transportation(bus, U-bahn, tram) free-pass cards that can be use in Dusseldorf.
The most inconvenience point is that it has no elevators.
The excellent point is the breakfast. Coffee was good, and the buffet has plenty of breads, juices, yogurts, mueslis, half-boiled eggs and etc. It was a pleasant stay.