I'm not sure if it's the same excursion, but, we went to the Trunk Bay Snorkeling, and it was really nice. The snorkeling, and water conditions were ideal, especially if you are a newer snorkeler. We had beginners ranging in age from 5 to 65, and everyone enjoyed it. The crew was nice, the facility had showers and bathrooms. The ferry ride over had nice sights, and the "taxi" (it was a big open taxi that sat like 20) had great views. Got a lot of good pictures.
I don't have any experience with the other excursion to compare it for you, but, we weren't disappointed with Trunk Bay.