It was unpleasant to arrive at midnight, enter the room and see that it was used by the previous guests. I have never had this experience in a hotel in my life.
There was no formal excuse and we received a payment back from the reception because we requested and talked to them the next day (we were moved to another room, thanks there was one room available!). They should improve their customer relationships procedures.
The room was confortable, correct space and light. The room should have some maintenance retouches (oxide in the bath, painting in some parts).
The personnel of the restaurant is kind and the breakfast is standard.
Considering the area, it is at a nice spot, with parks around, and 10 minutes walking to the train station to Rotterdam center.