It was the best day of our trip in April. We adored it. A couple of other things to consider:
1. Make sure you stay there ALL day - don't get fooled that it doesn't seem that much to do. We missed all the educational things we wanted to do (in the education cabana) because we were doing all the main activities. Show up at 8 am so you can be registered, suited up, fed and ready by the 9 am "opening time"
2. They will feed and hydrate you all day. The food is good but not great, but remember, you would be spending money on food, drinks, and snacks elsewhere.
3. One of the big expenses there is adventure photo - they take beautiful photos and an OK video. I would recommend getting the CD of your photos (not prints) (I can't recall how much this was maybe someone else remembers, maybe $75) + the video if you want it. Then make sure they take lots and lots of photos of your family - not just during your swim, but in the aviary and around the park. Be assertive in finding them.
4. Take advantage of the free admission to Sea World, Aquatica, or Busch Gardens - this could "earn back" half of what you pay.
I wasn't planning on going back until my twins become old enough to appreciate the dolphin swim, but with the new reef opening in June (when I will be in Orlando for a conference) I am seriously considering returning..... decisions, decisions.
I don't think you will regret it if you like animals. Just my opinion.