Stayed here recently whilst visiting Dokumenta 12. I found the room (number 110) to be very clean and although it was small it was absolutely fine. We were hardly there as we spent most of the time in Kassel and were on a flying visit.
The breakfast was a really good continental and considering we only paid £49 for the room including breakfast for two I thought it was pretty good value.
The only slight hitch we had was when I booked I asked for a twin room (the girl on the desk's english was not great) and when we arrived it was a double. As they were fully booked they could not offer us an alternative. We were ok with this although it might have been different given a different set of circumstances.
We found the staff to be friendly although they had limited amounts of english.
Overall it was fine.
