Seems like maybe it will be a challenge to use, but like a lot of template stuff the complexity gets buried in the library. The language gets a lot of ridicule but I like the no-compromise push to help programmers eliminate unnecessary runtime work in their programs.
The corollary of that is that most new c++ features get designed with the explicit intent of getting burried in std library implementation (with coroutines being excellent example).
Then, developer is presented with a nice, easy to use library interface, that violently explodes all the obscure implementation details in their face on first error.
Modern C++ is made, I feel, primarily to make STL implementation less embarrassing.