This looks nice to me. Sort of reminds me of cython and to a lesser extent nim. And I sort of like cython, except I rarely end up using it in practice because I find that you end up dealing with three languages - python, cython and C - or even four, if you're also trying to use C++. (At least back when I was using it, direct cython to C++ interfacing wasn't available yet). And the borders between them were a bit fuzzy sometimes - you'd have to see the compiled C output to find out where you forgot to cdef a variable. If you use pybind11 then you just have to deal with python and C++ (though admittedly the metatemplate programming used for wrapping is a bit of wizardry).

So getting better performance in a single python-ish language with a bit of extra syntax seems promising to me, but I admit I've yet to try this. I'll wait to see if a good ecosystem gets built around it.