This was only my second cruise, the first being the Carnival Freedom in April 2016. The Vista may be the biggest and one of the newest ships in Carnivals fleet, but overall it was very hit or miss.
Pros-
More dining choices, things like pizza, burgers, and tacos on the Lido deck come with no extra fee. There is also of course the buffet on the Lido deck, the breakfast buffet is pretty good, with a large selection of items including dry cereal, pancakes, french roast, bagels, grits, fresh fruit, yogurt, etc. Lunch and dinner items on the buffet okay, there were a few good offering, but mostly it was lack luster. Bonsai Sushi, Pig & Anchor BBQ, Fahrenheit 555 Steakhouse, and a couple others are not complimentary. Personally I only tried Bonsai Sushi which was quite good, I had their Chicken Katsu, Two plates or sashimi, and the yuzu custard. The chicken Katsu wasn't anything special, but the sashimi and yuzu custard were both delicious and fresh. I was cruising with some friends who tried Pig and Anchor, which they gave mixed reviews.
Miami has a lot to enjoy, I actually spent two days in the city before the cruise. Nice Beaches, lots of dining options, and it doesn't feel touristy.