I did this many, many years ago, so I'm not sure how much it has changed if any. The first part of the tour is spent in a backstage classroom where you learn about dolphins, conservation and the Disney program. You may also get a small tour as you head backstage. You then go on stage to the large viewing windows where you continue to learn more about the dolphins and the research done there. The last 45 minutes or so, you don a shorty wet suit and go to the top middle of the donut shaped aquarium. As a group, you step out onto a wide ledge in waist deep water that extends out into the aquarium. They then bring one or two dolphins to you where you have some one on one contact. You are able to pet them , maybe even splash back at them if they splash you but that's about it. They also take a photo of you with them and get a t-shirt as well. If you are expecting a lot of tricks, playing and swimming with them like some other resorts, then you will be disappointed. If you will not have a chance any other time to interact with a dolphin, then yes its worth it. Also, it is very cool to go to the top of the aquarium which so few guests get to see. One thing that they always tell you is that it is strictly up to the dolphins whether they want to interact on any given day so there is no guarantees. I'm not sure what happens if they dont want to participate, but I personally have never heard of it happening.
I don,t know what the cost is now, but back then, was it worth it? Yeah. I then took the Seas Aqua tour a year later, and that gave me the bug to become a certified diver. The year after that, I dove the Living seas, and that was pretty cool also. So try it, you'll never know where it will lead you.
Hope this helps!