Looked into it when I was younger, around 18/19. After talking to a few people who had done it previously, decided that definitely wasn't for me. Work like a slave, get shitty sleeping accommodations, almost no time off, have to put up with arrogant dickheads who think they own the world because they're on their 5 day a year vacation, etc.
They don't tell you that in the, "Travel the world. Apply for ABC cruise lines today! All expenses paid!" classifieds in the newspapers though.