My kids would have been super bummed as well ... and I would have been irritated. You don't go to Aulani because it's a water park, but the slides are heavily featured in promotional material and big selling point for families with kids, so you would expect them to be operational. It costs a fortune to get to Aulani and then it costs a fortune to stay there ... to have one of two slides closed would be a bummer and you have every right to be disappointed. Especially since there was no notice!