I stayed on the SS Rotterdam for 2 nights since a conference I was attending was taking place on the ship. It was kind of cool to have it on a boat and getting to stay on the boat is a bit different too. The boat is absolutely huge. I unfortunately didn't get to see too much of the boat since I was attending the conference most of the time. But I can say that the food was alright for the Netherlands. A huge breakfast spread, the usual sandwiches, savoury pastries and milk at lunchtime and a nice variety of food at dinner where there was the conference social event. Service was quite good I found during all of the food service times.
My room was big for a boat room (they are usually tiny), but I did have a superior room. It was clean and the bed was comfortable. Of course, the windows don't open since it's a boat. The mini-library in my room was a nice touch, but too bad I don't know any Dutch! The doors aren't that sound proof and you really hear it when people walk by in the hallway or close their doors. The cleaning staff for some reason also came knocking on all of the doors in the morning which I am sure is disruptive for those who want to sleep in.
For those here to really visit Rotterdam itself, it's not exactly an ideal location since it's not in the centre and not close to public transport, so you will either need a car, or do as the Dutch do and ride a bike.
But overall, I did enjoy the stay here since it's not every day that I get to stay in a hotel on a boat.