My husband and I did Dolphins in Depths last year....we LOVED it!! It's a 3 hour tour. We learned about their what they do as far as training goes, conservation, dolphin anatomy, etc. We also got to watch a training session. We spent about 20-30 minutes in the water with the two dolphins. You get to take a photo with the dolphins...either on your own or with whoever you came with. At the end, you receive the photo, a tshirt that has the DID logo and says "Disney's Dolphins in Depth" and a booklet that talks about conservation.
The tour is $150 and I personally felt it was absolutely worth it. The Birnbaum's Guide to WDW has a 15% off coupon that's good for up to 4 people. All the proceeds of the tour goes to conservation...which makes it worth it even more.