My wife and I had a great honeymoon cruise on MSC Preziosa. Took the plane to Milano, went to Centrale station and then took a train to Genova, Piazza Principe.
On account of the wedding trip we got a discount (on net price, without the ship taxes and tip amounts) and a complementary champagne and fruit plate on board.
This was our first cruise and I'd say my strongest impressions would be these:
Great city to visit, a bit of a hassle to get to city centre - one bus ride to terminal border, another bus ride to train station, a train ride to downtown. Same trip backwards.
Really convenient, the ship docks at a walking distance from main city sites.
Pleasant stay, only a short bus ride from ship to cruise terminal.
Great city, the cleanest on the tour. Takes a somewhat short bus ride to get to main sites.