My DS did this last year, and while it was "fun" he didn't like it at all. I think mostly he was scared of being by himself ( no mom or dad ). He had just a few days before turned 5, that may have been the problem. I think for older kids it's wonderful. You take the kids to the GF Marina and they get outfitted as "pirates", they get pirate hats and you get a pager/beeper. They board the boat with a "buddy", another child, and off they go, singing pirate songs. They get lunch and a pirate treasure, a little box with some rings and stuff, this is not major stuff, but the little one's like it. My DS loved that part!!! LOL They go to different areas on the lake, and get off the boat, scour the beaches and hunt for treasure, then they return at a set time. I think if my DS had been a year or 2 older he would've really loved it, he still talks about it, ( a year later ) and says he liked it, but he didn't that day!! If you are thinking about it, you really should book it early, I called 90 days out and they had 1 reservation left for the day we wanted!!! I'd say let your child do it, I only wish we had waited a year or two. I'd say between 6 and 8, it would be ideal. The kids older than that didn't seem too excited about it when the boat pulled in!!
Hope that helps!!