You can easily spend a day at WnW, and you should easily have time to do all the rides. The newest, The Storm, is very exciting and just a bit scary -- it zipps you around inside a big bowl before dumping you out through a hole at the bottom.
WnW is like a Disney water park without the themeing and many people who like their water parks straight prefer it to Disney's versions. It's popular with teens in the Orlando area and until just recently had larger attendance than the Disney parks.