Overall a great experience!
We saw several groups of dolphins during the half hour or so we cruised around watching, some less than a few yards from the boat.
Snorkeling was great as well. All gear provided was in good working order and fit comfortably. The reef was fantastic, with fish laden corals only a few feet beneath the waves.
The only complaint I'd have is that being a combination trip you may be left wanting for more of each at the end. So if you think you'll enjoy snorkeling or dolphins more I'd recommend a specialized tour, or if you have a longer stay do both instead of a combo. But for us, on a short trip, it was perfect!