I can tell the nationality of every single person giving 1* because of the whining and lack of education they espouse. Ignore the troglodytes. FYI the waterfall volume is determined by rainfall - dry season it will be a trickle. Go figure. As for wearing flip-flops to a rainforest? You get what you get. Wear sensible shoes or you'll slip, trip, or get bitten by something. Common sense.
Rehabilitation of wildlife is really expensive. 1,000baht per person isn't cheap, but it all goes to helping them. This isn't a zoo. You won't get to hold them. You won't get loads of close up photos. That isn't what this place is about and that is exactly why it's the best tourist attraction on Phuket. The vast majority of tourist places on Phuket exploit and actively harm their animals (Tiger Kingdom, most of the elephant sanctuaries, Fantasea etc - never go to these places). This place is the opposite, and it's run by a fantastic, passionate biologist who loves what he does.
This is conservation in its purest form. Observing the enclosures at a distance, catching glimpses of the wild ones if you are very lucky, and enjoying learning about the gibbons in their care.
National Park entry is 200baht which goes towards running the jungle itself and maintaining paths, car parks etc. I got a taxi there from Bang Tao for 700baht which was expensive because of the storm and surge pricing. You can get it for 250ish no problem. There is a food stall in the car park with basic toilets. You can get mosquito spray from the project building once you've signed in.
We had five on our tour - me and a family of four with two young kids. The guide was funny, informative, and passionate. He was so good with the kids that even me as a former teacher was impressed. We also saw an orb weaver spider, loads of butterflies, black termites, various grasshoppers, and a wild monkey, as well as about 12 gibbons in total. The gibbons are at a distance because they're being taught not to rely on humans who have abused them. This is the gold standard of rehabilitation and conservation and I am disgusted anyone would give this place 1*. The paths are concrete but they are mossy, uneven, and slippery, so wear suitable footwear.
I could not recommend this place more to any tourist with more than two braincells. If you have fewer, stay at home with your MAGA hat on, cheering the invasion of Palestine or Ukraine. Everyone else, visit and enjoy!