Imagine an inverted aquarium! From the beach in Waikiki you are ferried out to a submarine which goes down a little more than 100 feet and then cruises around the ocean floor for about 45 minutes.
The company makes no bones about the fact that the reefs are artificial and that the ship was cleaned and moved there. The idea is to attract marine life in a non-invasive way, and they do a good job. On the ferry they have complimentary cards which show the animals which you are likely to see.
Bailey, our guide, was very knowledgeable and, of course, witty, which seems to be mandatory in her line of work. The rest of the crew was also very good.
It is what it is. The submarine was comfortable and clean and it was a nice way to spend a couple of hours. Ultimately you're paying for an external aquarium. If you're happy with that, then by all means sign up. All the animals are free to come and go as they wish, and while it's possible for zoos, it's very unusual for an aquarium. Not sure how better to say it: if you're willing to meet the attraction where it is, you'll have a great time. If you expect much more than it is willing to offer, you'll be disappointed.