Yes, $45 per person is a lot to pay for a day pass admission (I was not a guest at the resort, and this was a pass only for grounds and marine habitat access), but it was totally worth it!
I love marine life and aquariums, and this was an amazing experience. Exhibits were very well-made and there was a terrific diversity of marine life including a manta ray (awesome!), a hammerhead shark, sawfish, nurse sharks, and sea turtles. Was a little bit "Disney theme park-like" in some areas, but it was really very well done.
I only wish that there was more information at the exhibits to identify what you are looking at. Also, I thought that there was poor signage/directions at the resort. Not easy to follow the map that was provided, and the exhibits were not clearly marked (the map was marked, but when I got to an exhibit, I wasn't sure which one it was).
As I did not stay at the Atlantis resort and came on a cruise, I purchased one of the day passes. Yes, it was very expensive, but completely worth it. I was able to see all the exhibits in the one day I was there, but it did involve a lot of walking, and I was quite exhausted at the end of the day.
If you are staying at the resort or just stopping by for the day, be sure to take time to see these amazing exhibits. There is so much to see that I could have spent another day exploring it all. If I ever come back, I may even try to book one of the snorkeling trips in the exhibits (not sure how much it costs, but I think it would be an amazing experience).
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.