We just got back from our third Princess cruise. This one, on the Diamond, was fantastic. I travelled with my wife and two children (ages 12 and 9) and we were joined by another couple with similarly aged children. It was Spring Break (900 kids on board). Princess now has Youth Security...guards in yellow shirts that watch the children. The guards kept the kids from running around the pools and down the halls and stairways.
I recommend that you read the other reviews. They are quite helpful. Rather than repeat what has already been said, I simply want to make a few observations.
We previously cruised the Caribbean. We loved the Islands and the beaches. Mexico is not the same destination. If you are looking for Caribbean shopping and Caribbean beaches, I suggest you go to the Caribbean. Mexico is very different and your Mexican vacation will differ from a trip to the Caribbean. We met many people who didn't bother to get off the ship at any of the ports.