Just being on board a ship with 5,999 other passengers would be enough to put me off!
Incidentally, during the recent Sea Diamond emergency it apparently took 3 hours to evacuate the passengers which was in part due to the list as Bryan mentions. Obligingly, the ship remained afloat long enough to allow this to be done. These big cruise ships are essentially fair weather vessels which rely on forecasting to avoid storms. When they do get caught out they don't take the weather well judging by some of the clips I have seen. Too shallow draught and too high sided. The Berlitz Cruising Guide makes the point that older, deeper draught "traditional" ships are more sea kindly.