There's no catch but be mindful of park hours. Depending on when you are going, park hours could be 10am to 6pm. That's too late for most people to have breakfast at the park and it would be a challenge to have dinner because a lot of the food places close an hour or two before park close. That said, when I've done the dining deal, I've enjoyed the freedom to get unlimited free drinks (especially bottled water) all day and there are some good snack options too (fresh fruit, cookies etc).