I did Trainer for a Day in May. Let me preface my answer by saying that I also did a Trainer for a Day at the Mirage in Las Vegas and also did Marine Mammal Keeper at SeaWorld.
I personally was not super impressed by the Discovery Cove program. Don't get me wrong...the dolphin foot push at the end of the day and getting to swim in holding a dolphin's flippers was amazing. However, you don't get to spend the whole day around the dolphins or shadowing the trainers. It is basically a guided tour of the park and they do a few meet and greets with animals. We got to touch a shark and they brought a few smaller monkeys and an anteater out. We had a picture taken with them, but it was very quick. You did the 'normal' dolphin swim that everyone else does. At the end of the day you get to do the foot push that I talked about. You get a T-shirt and back pack.
The other thing that I didn't like was that they did not include any pictures. They took them, and then you had to pay extra. It cost me $200 for the DVD with pictures on, 6 8x6 pictures, a photo album, the video for the day and a poster print of one of the pics. The quality of the pictures was not very impressive. They do no cropping and no general editing. In a few of the pictures, my skin looked red.
For almost the same price, the one in Vegas provided so much more. You actually followed the trainers around all day, so you had a full day of interaction with the dolphins. They also included a dvd with all your pictures as well as an 8x10. Got a really nice polo short and hat.
Perhaps if I hadn't done the other program, I would feel differently. I liked marine mammal better.