My husband and I just returned from a 7 day cruise on Carnival Conquest. I wish I could tell you good things but I can't! We were first time cruiser and probably last time cruisers.
The check in and and check out went very fast with no problems. I had often heard of horror stories from friends about this but our experience with this was fine.
Being on the boat was a different story.. There isn't much to do unless your a gambler and enjoy smelling like an ash tray. :( The day time hours on the boat are very long and boring.. we were at sea 2 and 1/2 days before we reached the first series of ports. The activities they provide that are included are random info sessions on things like weight loss,detox, herbal remedies - which are really sales pitches to get you into their spa for a "free" consultation. They have silly games that they do on board which were not really appealing to me. You can only sit outside by the pool so long before that gets boring too. A lot of people seemed to be reading as a way to pass the time.