How good is the coverage of Apple Pay in China? Obviously not as good as Alipay. But is it useful?
Pretty useless I think. The use of Apple Pay is covered on the Apple's website in China. The list mainly consists of supermarkets, convenience stores, and malls, as well as some internationally recognized brands such as McDonald's, KFC, and H&M.
However, according to a question - How is your experience on Apple Pay in China - on a Chinese Q&A site, many users reported that the shop clerks don't know how to handle Apple Pay even though the shops adopt the system. Also, most clerks in China don't speak English.
So I recommend to carry enough cash, or create a bank account and Alipay or WeChat if you really want to use the mobile payment (which I did and you can even as a traveler).
I found that in most cases, the cards issued only in China can be used in China. I added my Amex to the wallet, but when I tried using it at a supermarket, the payment was rejected. In fact even App Store China requires a credit card issued in China...
as an avid Apple fan, Apple Pay is my preferred method of payment. Apple Pay is pretty useful in China. The QuickPass RFID terminals are basically in every major store. Notable exceptions are small local convenience stores, and of course every store/business that doesn’t accept credit/debit cards at all. That said, I would still recommend setting up WeChat and/or Alipay, for peer-to-Peer transactions and to be able to pay at the above-mentioned exceptions. I prefer Alipay over WeChat Pay, due to Alipay being more widespread.
Hope that helped.