Took my wife and 3 year old son. We had a blast. The tour was really fun, and the crew was great.
I'm not certain why, but my wife and I noticed that, if you purchase your tickets online through groupon (like we did) or even here on tripadvisor, you will pay $15 per ticket but when we arrived, the sign in front of the ticket booth says $10. Not a huge deal but I'm also not certain that we needed all the tickets we bought because the lady looking over our voucher made the comment that because our son was only 3, he didn't need to be on our ticket. (When we presented the voucher, she wrote on the ticket that their were only 2 passengers, not 3)
I can't recommend the tour enough, but I would call first to see how many tickets you actually need and how much the tickets actually are (and consider just buying them at the booth).