We did this excursion last October during our cruise. I think the name of the boat was the Seahorse. They used the boat's motor to get out to the reef and sailed back in.
I enjoyed this excursion, but honestly didn't think it was worth the money. The scenery is beautiful and sailing back was very cool, but the crew on the boat was less than friendly.
The reef they took us to was not that great, I don't know if all the reefs around the Bahamas are like that or not. It was my first time snorkeling in the Bahamas, but I have snorkeled in Mexico a few times.
There were plenty of fish, but they weren't very colorful for the most part. They do sell fish food on the boat before you dive.
My 12yr. DD had a great time, so if you are thinking of doing this for children it might be worth it. I just compare it to other snorkeling excursions I've done and don't think it was nearly as good, especially for the price they charge.
Hope this helps!