We did it last month and had a great time! That said, I wouldn't really recommend it for families bringing children, as ours had a lot more of a "booze cruise" kind of vibe (though with the group we ended up with, lots of friends were quickly made and it was an absolute blast!). I suppose that would vary with the mix of guests onboard, but that is just my opinion based on our experience. As an example, I think three trays full of shots went around on our sailing - in addition to bahama mamas and other mixed drinks.
The snorkeling stop was about 45 minutes (if you want to snorkel, you will not be served alcohol until after you do your snorkeling), lunch was so/so, I wasn't a huge fan but it is a short excursion so not a big deal. Snorkel gear is provided but we brought our own and were allowed to use it. There isn't anywhere to secure your bags near the front of the boat so be prepared to hold on to them. Where on the boat you sit is first come, first served. On our way to the snorkel site, we got a great little history/sightseeing tour from one of the guides. Overall it was a wonderful excursion for us and I would book it again. You do get dropped off in a different place from where you board, so it is a little bit of a walk to get back to the ship.