Based on an extremely quick skim, this appears aimed only at projects that are using autoconf purely for portability across standard Unix environments. It admits up front that it drops features that people find valuable about configure, like --prefix et al and the entire feature selection cluster of options (now you have to edit Makefiles, which has various issues), and it appears to have nothing for projects that need their own checks for additional features of the environment (OpenZFS being an extreme example). If I was being unkind, I would say it's an autoconf replacement for people who don't need autoconf to start with (and don't care about --prefix et al).
There is an ecological niche for 'you don't need autoconf' (and don't care about aspects it gives you for free), just like there's an ecological niche for 'you don't need Javascript', but I don't think it's a significant one.
