My two boys did it last year. They were 9 and 6. They had a great time. They all get pirate bandanas and go off on their 'ship' flying the skull & crossbones. When they came back they were loaded down with 'treasure' and singing pirate songs. Definitely a huge success.
My son done it last year (he was 8 at the time) and absolutely loved it. Has asked to do it again this year when we go in June. He said it was one of his favourite things of the whole trip. He also made friends with an American boy who he is still in touch with via email.