Chose this ship due to the South Pacific itinerary and based on a previous cruise with Princess (Regal Princess). In comparing the two ships, I was disappointed In the Ruby Princess. The entertainment was definitely not the same caliber as with the Regal in terms of variety or quality. The Horizon buffet court had much less selection and was poorly staffed. Often multiple serving sections were closed creating long lines to get your food. They also kept running out of certain types of food (granola would be one example).
I would give the dining rooms in the Ruby an edge over the Regal though.
Much less options for day time entertainment during sea days and the options they did offer was not that strong. Evening entertainment was often single entertainers and very little production shows. The Ruby Princess band however was TOP NOTCH - very impressive!!! Finally the senior staff were pretty invisible- very little interaction with the passengers.