If you are a stick in the mud and don't like seeing other passengers having fun and like to complain about everything then you won't be happy with Carnival or any other cruise line.
We were on the Crown Princess using the anytime dining. There was a snobbish couple sitting in the table next to us that was basically the long booth type seat along the way and small tables for two set along it so you couldn't help but be part of the conversation. All they did was complain about everything and how much greater Crystal was. Of course it had to be better look at the price difference.
Take the cruise and don't let others influence your attitude. When it is over you can decide for yourself. I haven't had a problem with any of the cruise lines. I just go with the flow and enjoy. Like they say if you have lemons make lemonade.