I stayed there during the european song contest in Dusseldorf this year. Hotel was not as full as expected so I got jr. suite on third floor next to the corner facing the Dome. Hotel staff is pretty friendly and rooms are renovated (at least if you get one of these). But it also has its historical charme on the corridors. When I was there they elevators underwent a renovation so only one that is very slow was in operations.

Breakfast was included in my rate and was pretty good.
For platinums "only" room upgrade to jr. suite and standard amenities. Local gift was a small block of stone form the Dome.