Really cool experience. We visiting in early March. We had two 9-10 foot Galapagos sharks swimming around the cage. First time we've done such a thing, so it was a really cool experience.
Other reviews warn about sea sickness. We didn't experience this as we had a calmer day. But the boat driver did warn that it does get bad sometimes.
As for being in the cage, it's awesome and awe-inspiring. You have 20 minutes in the cage. They provide snorkel gear so you can go underwater. The cage floats at the top, so you can stay on the surface, if you want, but best to dive down a little to see the sharks. Just a really unique, cool experience.
One kind of weird sidenote. Our cage was missing a bar. In its place, they had a roped taped up to both sides. OK then? I guess it shows they aren't worried about the sharks coming into the cage.