Wouldn't be good for protestors. Wouldn't be good for anarchists. Wouldn't be good for people using someone else's ID for transit. If you're on this site, chances are you wouldn't be getting tax breaks for community service; you'd be getting blacklisted from trains for jaywalking or missing a dinner reservation. Like fuck, I'd consider myself a Tankie, but I don't see an upside remotely worth the cost of this.
Not to mention the surveillance required to make social credit viable. 'Actual credit in America is even worse!' is a bullshit argument too.
In the west if you wish to get a loan, rent a place, get a phone etc. most countries will ask for bank statements, bills and other evidence that you have money and will be able to pay for things. When businesses make deals there's usually laws involved that require the businesses to be open about their finances to prevent anything dodgy. When going for a job many places want a background check, references and will usually look at your social media profiles (facebook, linkedin etc) as well as all the information you give on your resume. All your information is out there and judged before making any major decisions in life. China want to build trust by creating a credit system that basically puts all these things into one. All these systems are stupid and anti poor.