Hanks advice on keeping your valuables in hand is very good advice. Don't use the overhead compartments or set things like laptop cases, purses or camera equipment on the seat beside you. You may never see it again.
Also his post makes very clear to all who plan to fly in to Rome and depart on a ship how little time you have for sightseeing unless you plan one or more night hotel stay. Transportation will take up a lot of your time. The train ride from Rome to the port alone is actually almost 1.5 hours. Cruiseline transfers and taxis are quite costly as is nearly everything else in Europe. Planning well is important for cruises from Rome.