My family were there for opening day, 10/15. It was crazy but a lot of fun. We are a family of 5, with kids 10, 8, and 5. We all had a blast, even enjoyed walking around the old Cypress Gardens part.
There was plenty to do for the day but I think only one day is needed. I could have spent half the day just looking at the Miniland area.
We stayed at the Best Western that is right next to the property. I would not recommend that, however. It was old and needs a lot more fixing up.