It's called Librije's Zusje and is a "branch" of the 3star Librije in Zwolle.
I've had lunch there and it was good. I didn't find it spectacular but still very good. Looking at the menu for dinner that looks good too, but a little overpriced for my taste. Nothing unexpected for a restaurant in a hotel though....

But I would rather spend my money at Yamazato at the Okura that was also mentioned. Although they are also expensive, especially if you start on the sake....