This is for proposing legislation, not fixing local quality of life issues, and the success rate has been rather poor. China’s system has a broad scale, but is directed at local problems and has a very high success rate.
As I understand it, many of the issues faced by petitioners in the past were due to local corruption; officials would physically prevent petitioners from traveling to the petition office to deliver a complaint. The new systems (12345, 12388, and the apps) are intended to bypass that and have done a decent job at reducing corruption.
The Citizen’s Initiative is more of a referendum system for proposing bills, but due to its non-binding nature those bills are often ignored. China’s system doesn’t necessarily bind the government to action either, but given the small scale of the problems they are motivated to fix them.
This does not excuse China’s human rights abuses, but if you’re going to be abused either way, I can see why some would prefer to do it in a place with a rising standard of living and with a government that seems interested in improving.