The tour is exactly as advertised, but the tripadvisor page doesn't give you all of the details. This is one of those "tourist trap" kind of situations where once you're on Green Island everything costs extra money. I expected that going into it, but just be aware that's what you're getting yourself into. For example the included snorkeling does not include wet suit to protect from stinging wildlife nor does it include a life vest for easier flotation - those cost extra.
Things I liked:
1. The glass bottom boat tour was fun and the tour guide was a marine biologist who is very knowledgeable and friendly.
2. Access to the Green Island Resort pool is included so you can spend time relaxing in and around the pool area for no extra cost.
3. Green Island is a tropical island far from the mainland, no street noise or other distractions out there. It's easy to find a peaceful spot and relax.
4. There is cell phone reception on Green Island (at least there was for me - I was using AT&T International plan)
5. The ferry from the mainland was comfortable and the crew were helpful in telling us what to expect and how to stay safe while doing the activities provided.
6. Free water is available at the bar near the pool.
7. One of the restaurants serves a "seafood basket" which has excellent calamari, or at least it was great when we visited.
Things I didn't like:
1. The glass bottom boat tour doesn't last very long - maybe an hour at most and it stays close to Green Island, you won't see any other parts of the reef.
2. Finding the spot where you check in is not as easy as it could be. You have to realize that you're not looking for "Great Adventures" you have to look for signs for the actual company name on your reservation.
3. They start boarding early so you need to get to the check in spot extra early just in case.
4. You can leave early if you want to but the tripadvisor page doesn't say that. You don't have to stay the full 8 hours, ferry goes back to the mainland a few times during the day.
5. Regarding the pool area, towels are NOT provided. If you don't bring your own you won't have any. The chairs are mostly not padded and will get very hot if left in the sun.
6. As I mentioned - food, drinks, etc. on Green Island are pricey due to this being a tourist spot and resort.