They’re fine to my eye, at least as good as well tuned freetype (as found on Ubuntu) as long as you’re either using a 2x HiDPI display or are using a “normal” DPI monitor with above average density (e.g. 2560x1440 27”) and have subpixel AA forced on.

Where it falls apart is at densities any lower, for example it struggles on those awful 1366x768 15.6” panels that it seemed like every other laptop was built with for a while. Similarly 24” 1080p and 32” 2560x1440 are pretty bad.