My partner and I cruised with Royal Caribbean's Liberty of the Seas from Naples (7 nights) in July 2013. He had never been on a cruise before, but I had a rough idea of what to expect having been on two previous cruises.
The food was decent (at least from a North American perspective). The service was great. In general, there were enough things to do on the boat.
What we thought was ridiculous, however, was the constant upselling and pressure sales that we faced throughout the cruise. I couldn't believe how much they expected you to shell out extra every day. I couldn't even enjoy the spa without having a shady "doctor" tell me my 29 year old face needs 1200$ of injections, or the massage therapist try to pressure me into purchasing massage oil to release "lactic acid" in my back (which is a load of BS, btw). Another thing was, in the evening, there were very few things to do on the boat that didn't essentially require you to purchase something extra. You can't go to a night club or a lounge and just sit there empty handed (well, you technically can, but that seems rather odd, doesn't it?). The movies they played were the same that were constantly on in the room on what seemed like a loop. We felt that by 10pm there was nothing left to do unless we wanted to spend extra money.
So, over all, if money isn't an issue, and you don't mind spending 50% + more than your original cruise price on drinks, gratuities (aka shameful exploitation of workers subsidized through 12USD per person per day), and other activities, this cruise company is decent.
One other thing to point out, and I am sure this is the same for all companies - you CAN do the port excursions on your own! For example: Save yourself 90USD per person(!!?!?) on the train trip from Civitavecchia to Rome by purchasing the tickets from any Italian train station (or online) prior. It costs 5 euros per person and you can easily walk from the port to the train station... and its the SAME train that the cruise company uses. The same goes in Le Spezia and Villefrance. Infact, you don't even really need to buy the tickets in advance, it just saves some stress and trouble the day at the port. Barcelona you can take a taxi for about 15 Euros into the central part of the city. Buy your tickets in advance online at Sagrada Familia and for the Vatican Museum and you won't wait in line. My point is, don't allow the cruise companies to rip you off to such a degree, do some research and you can save a lot of money.