When we drove up, we thought it was closed, as there wasn't a car there! However a bunch of people showed up while we were in the "hamster ball", and it sounds like the traffic fluctuates a lot during the day. Good not to have to wait!
The balls are getting old and yellow, as mentioned by a previous poster. Apparently they are about 2yrs. You can hire shorts, shirt and towel for $5, or $2 for any one item.
We were driven up the hill in an AWD and the guide filled the bottom of the ball with warm water. We chose to go in together (they said its more fun with two), and they also gave my husband a Go Pro to video from the inside on the way down.
My husband had been skeptical, but it was so much fun! You actually hear him say on the video, just after we went through the gates "ok, this is awesome" (in between all the laughing).
You don't get too tangled, because the warm water keeps you sitting in the bottom while you roll. Straight down (40sec) was probably a bit more fun, but the sidewinder (2min) was also great, as when the ball slows you can throw your weight forward to help it along. I'd recommend trying both if you can afford it.
The crew also jump right in when the ball stops, and get some great photos of you in the ball, getting out, and grinning like an idiot straight afterwards.
There's a hot tub you can soak in to stay warm between rides/after.
Photos were NZ25 or NZ40 inc video; pretty good value I think. Originally against buying video footage, we took the camera in anyway and the footage was so funny we decided to get it anyway.
Fun for any age, couldn't recommend it more.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.