We have sailed with Carnval three times and once with Princess. What a difference your destination makes! We sailed the Mexican Riviera twice and Alaska once. Honestly, each time I had wanted to go to the Caribbean, however due to where we live it's a bit on the spendy side for airfare. Mexico has always been beautiful and we really enjoyed our cruises there. This time we went to the Western Caribbean, and had a blast on the Conquest!
We have always had a pleasant experience with Carnival. My hub have gone online and in reading reviews about Carnival, and the Conquest specifically, we have come to the conclusion that it is HARD to please everyone! Granted, if you look for things to be wrong, at anytime anywhere for any experience in life, you're going to find things. We notice that some things that get on our nerves that are not the cruise line's fault. For instance, line-cutters, non hand washers, and deck lounge chair reservers that are mostly absent.
Also, to be honest, the food in the buffet could stand some changing up, and I miss the free espresso in the dining room. But these are all very small things that really don't have to affect your vacation!