Yes, we have, and lots and lots of other people. I imagine there are threads full of info on this. People seem to get a variety of prices, but all cheaper than doing it through Disney. It's easy to get (or share) a cab with others on your cruise (post about it on your meet thread) and go over to the hotel, spend about 20 minutes getting checked in and out, and then another 10 minutes walking over to the park.
It's a nice place, but no where near as nice as the Disney water parks.