I'm a big Carnival fan, but my first impressions are, at best, meh.
The ship is going to be CROWDED - there's simply no way around it with the passenger space ratio being what it is.
And where have you gone, Havana Pool? A tiiiiiiiny pool on Deck 8, no hot tubs, but a heckuva lot more Havana cabins than on Vista class. The Havana area was the best part of my cruise on Horizon - after a tranquil, relaxing day hanging out around the Havana Pool, a trip up to the crowded, frantic, and noisy Lido deck for a Guy's burger made me want to skip the food and run for my life.
The Neighborhoods....whoops....Zones look OK but they are definitely derivative.
I don't really see anything here that makes me want to cruise on Mardi Gras instead of any number of other Carnival ships.