Earlier quoted context omitted.
It is no longer great (it used to be so around Mavericks). Current pdfkit is broken, and renders PDFs blurry, with the effect enhanced on low PPI screens. This holds for iOS as well since the same pdfkit is used, but since the devices running those are extremely high PPI this bug goes unnoticed by all but those looking for it or those with sensitivity to such imperfections. I think the state of PDF rendering on macOS…
Do you have screenshots that can demonstrate this? I'm surprised to hear it, I'm fairly picky about visual quality but I've never noticed an issue with PDFs on MacOS or iOS. Never used a low PPI screen with them though.
https://apple.stackexchange.com/questions/295427/what-causes...
https://discussions.apple.com/thread/8531638
https://twitter.com/deivi_dragon/status/938663751158501376
https://www.reddit.com/r/apple/comments/72lxjx/macos_high_si...
It is less visible on a high PPI screen although still there and noticable if you know it exists. Unfortunately I know it exists, can see it and am bothered, so I stopped using my Macbook and left it to collect dust.