Apparently they have started to renovate their hotel rooms with about 40 now ready.
As I read this on TripAdvisor I contacted the hotel via Facebook to see if its possible to get one of the newly renovated rooms for my stay tonight.
Dear Thomas199023. Of course you can also stay in one of our 40 newly refurbished rooms next week. We made a note in your reservation and also the Front Office staff was informed. Looking forward to your feedback - I hope you will enjoy it. Have a save journey to Dusseldorf.
I never minded the "old" rooms but I agree that a renovation was long overdue. I'll report back with photos of the new room. (if I actually get one)