We stayed there in March, but didn't use the waterpark at that time but used it the previous time we were there. It is really nice for younger kids. Our friends' 6 kids, ages 3 - 11 enjoyed it. There's no thrill slides, just small ones, there's a lazy river, zero entry pool area, water playground etc. There's also kids activities that you have to pay for going on throughout the day.
The homes are anywhere from great to amazing. Make sure that the waterpark is included in your rental. Reunion management have changed the rules allowing home owner's guests full access to the waterpark, so just ask and make sure when you inquire.