Just got back from a 2 night stay at this property and it has far exceeded my expectations as a long time Globalist and Hyatt hotel explorer in China.

First, this hotel is magnificently built and maintained. It's massive and feels like an architectural design masterpiece. There are Instagram worthy photo spots almost everywhere you look inside, not to mention the natural beauty of the Sunny Bay and outdoor pool areas, which are stunning. Yes, this tends to attract the social media influencers (or "wang hong" in Chinese) who are not only hogging up the photo spots, but also typically bring 2-3 of their camera-men along, so the hotel at times will feel a little bit less private and crowded because of them. Not a huge deal as you can simply ignore them. Note: the hotel is still in a gated off private area of Sanya with its own private beach, so you're already shielded from 99% of the huge typical tourist crowds of the city.

Second, if you search this hotel on Chinese social media and travel booking apps, you're going to see a TON of negative reviews and reports of incidents of bad service, poor room condition, awful experience, etc. Going into this stay, I was definitely concerned. But I quickly realized how exaggerated the negative reviews were, and now suspect foul play in many of the negative reviews written. Having lived in China for 10 years, here's my take on why so many negative reviews pop up for this property:
1) This is an expensive hotel by Chinese standards, so the typical Chinese guest who rarely stay at properties in this price range, are going to expect a heavenly palace-like experience for the money they paid.
2) Consumers in China are highly demanding of service people in general. Anything less than bend-the-knee type of service is going to offend them (ok I'm exaggerating here but it's not as far as you think from reality).
3) I wouldn't be surprised if some of the bad reviews originate from competitor properties. There are third-party contractors businesses can hire for cheap to generate this kind of bad press. And this type of malicious competition exists in almost every industry in China.
4) A big draw of this property is its architecture, you end up wondering how many staff hours and dollars are dedicated to just maintaining it on a daily basis. But this isn't going to impress most Chinese guests, who are used to seeing grand displays of infrastructure even in small tier 4-5 cities.