I live in China and has stayed at every single Aman hotel here. I even used to live in a gated community right next to the Amanyangyun in Shanghai.
None of them are absolute disasters except Aman Summer Palace which had the worst service and everything was wrong, but they are extremely overpriced and far from the group calibre.
The Aman Shanghai is probably the best out of the bunch but I found everything to be lackluster and is 2 hours away from any real part of the city