Hiya
I haven't personally but I attended a presentation by Steiner last year. One of my fellow students who attended with me took it further, but he decided not to follow it.
The problem as I see it is that in order to make any real money you have to sell products. You're working 12 hour days (which is illegal under UK law, considering the breaks they allow - but as Steiner is a US company and you're not actually working in the UK they get away with it) and there's literally no chance to escape, except to the other parts of the ship!
I'd encouraged my fellow students to do it, and to be honest if I was 21 again I would because it's a wonderful way to see the world and gain experience and training. However, you need to be prepared for this life.