We did it in January and I wasn't overly impressed. It's basically a beach day at a second rate beach with a chance to snorkle with the rays and feed them. You take a walk to the docks, board a boat, and ride about a half hour out to a small island. Theres a netted area to the left where the stingrays are, and a beach to the right. They give you a token for lunch and a drink, and set you on your way. We headed for the stingrays first, where my DS (5) enjoyed it for about 35 seconds, but the water was a little too deep for him, and the waves kept knocking him in the face every time he tried to bend down to touch a ray, and he got frustrated. He tried to be a trooper about it, and when it was time to feed the rays he gave it a shot, only to get cut on the leg but one of their tails (they're supposed to be de-barbed, but apparently this one wasn't). We gave up on the rays and spent the rest of our time on the beach until the boat came back to pick us up. I wasn't particularly impressed, and neither were many others on our excursion. I wouldn't spend the money to do the same one again. Next time, I'd either do Atlantis, or just stay on the boat and enjoy the pools and activities.
If you children are good strong swimmers and are REALLY interested in interacting with the rays it may be worth it for you, but make sure you take sand toys and stuff to keep everyone occupied on the beach-you won't be just swimming with them the whole time!