The reef was OK (Florida water is just too murky for really good snorkeling), but we saw a lot of coral and fish and had a close (but uneventful) encounter with a very curious barracuda.
Our 10 year old felt sea sick on the catamaran trip, but the rest of us were OK; the catamaran staff was nice and very professional.
My wife and I have been to other stingray cities including snorkel and scuba trips and this one seemed lame in comparison...it was a beach entry into a shallow area that had been fenced in with stingrays whose barbs had been removed for safety. Fortunately though, this turned out to be perfect for the kids who would have been freaked out meeting stingrays in the open ocean (as it was, they took some time to warm up to the rays)...we got to feed and pet and hold the rays and it was overall a good experience...we spent very little time on the beach and didn't think we missed much. If I had gone on the beach-only excursion, I would have felt ripped off.
We rented a waverunner (jet ski) from one of the local guys and that was the highlight of the excursion for the kids.
I thought the captain of the pontoon boat that took us to and from the island made some inappropriate comments to (at least) one of the teenage girls...she took it in stride, but I think RCI should work with their contractors on this excursion to be more professional. The folks working the beach were also not very professional...overall, this seemed like a very low budget operation.
We walked around Nassau briefly after returning from the excursion, but downtown Nassau is mostly a tourist trap and we have been there many times so we didn't spend much time there...it's a good place to buy shirts for the folks back home.
The kids went on the water slide (OK, but not like a real water park); our 10 yr old thought the line was too long for a relatively short ride, but our 8 yr old really enjoyed it. I'd guess about 5-10 minutes between slides.
We went to one of the many beach areas and rented floating mats which were very nice and did some snorkeling; this was actually much nicer than it sounds because the scenery and water were spectacular; others found many live conches, starfish, and we saw a wide variety of fish, rays, etc.
Coco Cay is a really nice destination and an ideal day at the beach (it's going to be hard to take the kids to Maryland/Virginia beaches after this). The private island was also very nice; I felt perfectly safe leaving my camera and things on the beach while I went snorkeling with the kids...I would not have felt that way on a public beach. We brought some small kites and the kids flew them for a while which was fun as well.
The staff served an impressive meal on the island although this was the only meal with a very limited vegetarian selection.
The kids' water park seemed lame and overpriced for 1 hour access. When we were leaving, we noticed that they had sailboats and jet skis for rent; I didn't try these but would have liked to.
Recommended: Instead we booked surfing lessons with Nex Generation Surf School (http://www.nexgensurf.com). We took a taxi to meet the owner (Brian) near Ron Jon's; none of us have ever touched a surfboard, but Brian and his assistant Eli were patient and great with the kids and we really enjoyed it. They supplied everything (including wetsuits, which kept us toasty warm in the chilly November water). Brian gave us a safety talk, taught us how to get up on the board when we catch a wave, and then took us out in the surf. With Brian's help, our 10 yr old got up on the board quickly and looked good. Our 8 yr old got up as well with a little more help (Brian was excellent with the kids). I eventually got up on the board too...it wasn't pretty, but it sure was fun. We'll probably try this again, perhaps in the spring or summer when the water isn't quite as rough, it's easy to see how people can get addicted to surfing.
If you're going to Port Canaveral, this is a great way to spend your excursion.