Yeah. It's not for everyone. I think "different ergonomic issues" may cover that and I did mention the type checking already. :-)
It is a smaller learning curve from pure C than "all of Rust" or even "all of C++/STL". You got the basic idea in short order (that may be for ill as well as good..I was never trying to make a normative claim).
Having a type declaration dependent on #define P whether it is plain old data or not, and needing to know what that means, is not the kind of ergonomics I'd want. That requires learning a whole new paradigm to ensure I am not doing wrong things.
In my mind it is so big an extension of the C language, that it leaves the C headspace and becomes its own headspace.