Do you think it is harder to learn than Ocaml/ReasonML though?
I think there is a good free introductory book [1], a welcoming community [2], the language and ecosystem are quite stable nowadays and there's good tooling (now that there's the Spago package manager).
It's definitely harder. I have been doing O'caml for about 20 years now, and we have probably one of the largest Elm apps out there. I looked at Purescript, especially because it also compiles to other languages (C++, BEAM) but the learning curve is a bit steep.