I've been on the beta for a couple days (using a 2016 12" MacBook) and I haven't noticed anything. There's a visible difference when I disable LCD font smoothing in settings, but not much changes besides fonts appearing somewhat thinner.
I installed Mojave beta on my MacBook Pro. It is the same thing. The fonts look identical to toggling off the setting "Use LCD font smoothing when available" in High Sierra. And by the same thing, I mean they look very bad in Mojave.