We did that excursion this October. I read a few of the older reviews, and they are still pretty accurate.
We spent 45 minutes at the turtle farm, where the kids were able to get into one of the pools and hold the turtles. At the dolphin swim, there is a lot of waiting around. However, I will say that getting a belly ride from the dolphin and having it push you on a boogie board made it all worth it for us. The pictures of our kids doing that are priceless and totally made it worth it to us.
Speaking of pictures, you will not be allowed to use your camera at the dolphin swim (even waterproof ones) because they want you to buy theirs. Be prepared for sticker shock, and get ready to negotiate. Their opening offer was $250 for prints and a CD of all our pictures (we heard some families quoted $500). IIRC, unless you just wanted one or two pictures, they charged based on the number in your party, not how many pictures you were getting. We ended up paying $180 for just a CD with over 100 pictures. They test the CD in front of you before you leave to prove that it works.