We just got back from our cruise on the Dream and did this excursion. We didn't do the deluxe version (which included lunch), we just did the regular version.
We walked off the Dream (with Disney towels they handed out) at about 9:45 and were led to a smaller boat with our group of about 25 people. It was about a 25 minute boat ride to Balmoral Island. The one end of the island is a Sandals resort (you could see the big sign once you got close to the island). We docked on the other end of the island and were told when the shuttle boats were returning (ours was at 2:45 IIRC).
Once we walked off the boat we were free to grab a lounge chair near the beach. There were about four rows of chairs on a nice white sand beach. There were a few people already there, but not many. We snagged some lounge chairs on the second row. The kids went and played in the sand/water. There are drinks (including Starbucks) and food available for purchase if you did not buy the deluxe package. People there were also doing dolphin and sting ray encounters, but I don't recall that being an option with the Disney excursion. I presume you could add it there if you wanted to.
The people next to us were also from the Dream and got the package that included lunch, so we saw what was offered. The kids had hot dogs or hamburgers with fries. The adults had salads or some type of sandwich. It looked like a decent amount of food, but since we didn't get it, I can't tell you how it tasted!
After about an hour and a half on the beach, the kids were bored and wanted to go back to the ship. We ended up leaving early on a shuttle boat with people from the NCL ship that was also docked in Nassau. It was not a problem to leave early.
Overall, I would say that it was a nice visit to a relatively uncrowded beach. But I don't think we would do it again.