we did a back to back trip from venice to split and then on to Greek Islands. The ship was packed. there were hundreds of children and 80+ teens - which was great for my teen up to a point.
The food was good with some bad/awful meals in the Grand Pacific. Very very slow service and very noisy. The Garden Cafe is a scrum. Free style dining is OK but it means being constantly surrounded by food and people eating giant plates of food.
We should probably have gone for a P and O cruise but we chose this one for the teen programme and my son age 16 said it was the best holiday of his life and he made a lot of friends quickly.