We arrived in Rome a day early, which I would suggest to anyone booking their own flights. We saved about $800 by booking our own air. Transfers to the airport are available through Carnival and Private Companies for about $60-100 per person. If you travel light you can take the train to the port, they leave every hour from Terminal Station, we paid 8 Eros for the trip. Arriving at the port city, it was about 1/4 mile to the free shuttle bus to the ship. Just leave the train station and walk north until you see the port entrance, the bus is just inside of the entrance.
Embarkation was super easy and quick, perfect. The ship is very large and the inside cabins are very acceptable, our only complaint was that the floor plan is a little confusing, but who cares, you are on vacation.
The entertainment was very good, just remember that it is "entertainment," so don't take it too seriously