Pros
You get to learn other people coming from various cultures and backgrounds, you learn how to work hard and play hard, you can build your career from bottom to the top if you "press" the right buttons, you get to visit some places, but for short period of time; company pays for your food, accommodation, visa, and flights, medical assistance while on board is free and very well organized.
Cons
Poor food in crew mess(fast food, frozen food, mostly represented by asian cuisine); big workload, working under the sun 8h a day (company doesn't provide shade I the most of the venues), average working hours from 8h per day recently increasing to 10h per day; poor management as company doesn't provide enough audit and training for managers and supervisors (favouritism, poor social skills, task oriented - never people oriented); uniform of poor quality and overpriced; no private life as you share a cabin; salary does'n reflect market trends such as inflation and risen cost of living; most of the times in port venues are open and empty, while its a great opportunity to give staff rest an time to go out