It is weird and inconsistent and I don't entirely put the blame on Chinese internet. I had the same experience but it seemed to me that problem more so was really badly written apps and services rather than the internet itself. Instead of just taking a little longer to load when loading is slow, apps will simply time out and make you try to load again. So rinse and repeat and nothing ever loads. Additionally apps and mini-apps (i.e. within WeChat/Alipay) seem to completely reload every time you open them rather than caching assets or anything.

So yeah, the experience absolutely sucks, but the problem doesn't seem to be the internet service itself.