We went to Cyrstal Palace for Dinner last year for the first time (coudn't get PS for Chef Mickey's at a reasonable time).
We thought the food was good, and saw all the characters twice (Pooh, Tigger, Piglet, and Eyeore) within 90 minutes.
Service was good (it's a buffet, all we needed was our plates to be taken from the table, and drinks refilled).
That being said, we found the atmoshphere and service at CM better (no one at CP offered to take our picture for us, while at CM this seemed to be standard operating procedure).