I want to start by saying there is nothing wrong with Carnival Destiny but I would rank it as a 3 star ship, nothing fancy, but good enough! They are missing some of the little extras that we saw on Royal Caribbean such as fruit carvings, the grandness of the dining room, the art available in the hallways and stairwells and that sort of thing. Nothing that would lessen your experience, just not as fancy.
ROOM - We upgraded to a suite from our standard balcony room (cost about $500 for the 5 nights) and it was worth every penny. We had priority check-in which resulted in no lines for us even though the regular line was wrapped around the building. That alone was worth the money. The room is also significantly larger. We were travelling with our 2 and 4 year olds and we had plenty of room for them to play in the cabin and the deck was big enough for everyone to sit on.
FOOD - the food was good. I would say it is about the same quality that you would get at a Dennys restaurant. The food in the main dining room is the same as what they serve on the buffet line and the presentation lacks a little. The food schedule is a little strange. There was a buffet line that served things like hot dogs and hamburgers that closed at 6pm so if you have a picky eater, you need to get there before it closes or they will have to eat of the main buffet line. There was only one formal night on our cruise and we noticed that most people were not really dressed up. Lots of golf shirts and sun dresses in the dining room. In fact, most people thought my husband worked there because he was in a suit!!