I have taken a few domestic flights the past couple of years, on Air China, China Southern, Hainan Airlines, and Shenzhen Airlines. In general, the Chinese airlines are investing in new aircraft that are comfortable. Service is good. The flights were all on or nearly on schedule (as opposed to CAAC 20 years ago, when 3 hours late was considered good).

The flight attendants try hard, and do speak basic English. The English can sometimes be VERY basic - last flight I was on, I asked for a Diet Coke. She did not understand. I also said Coke Light. Still did not understand. Unfortunately, while I know how to order Coke, beer, or water in Chinese, I do not know how to say Diet Coke.
Then, all of a sudden, the light bulb went on. She said, yes, we have it! She promptly came back with a glass of coconut juice! You just have to keep a sense of humour.

The food is not so great. I try to avoid the meals.

Overall, my experience has been as good or better than domestic US airlines.