I don't know if you are referring to the Serenade of the Seas or another ship, but a little over a week ago, we just got off. To say the least the ship was very smooth. The only time I noticed (I think I was the only one as I have a few problems) a little movement was a dinner one night, but it only lasted about 10 minutes.
We were in the Crown & Anchor area, and a question came up about the movement of the ship, asking the captain. He said this ship was very well balanced at the bottom (I could tell), so there would be very little or no movement that a person could detect.