I think it's very promising, but it definitely has some rough spots.

Things I like:

  * It's a general purpose language, it's not only usable on the front-end (like Elm for example).
  * It's a really powerful language (or rather, OCaml is).
  * Interop with JS is good. It takes a bit to get used to the syntax for writing bindings, but once you get the hang of it it's pretty straightforward. Again, ReasonML IMO scores a lot better in this front than Elm.
  * ReasonReact is a very thin wrapper around React, so if it's really easy to work with if you already know React.
  * There are other options than ReasonReact, for example bucklescript-tea [1] which is very Elm like.
  * There seems to be a lot of focus on targeting native. See for example Esy [2]. There's some real potential in bs-react-native [3] and Revery [4].
  * Overall the experience of working with Reason is really great. The compiler has your back, is great at type inference and the syntax is pretty elegant (though IMO a little less so than Elm).
  * The compiler is blazingfly fast. Blows Typescript and Babel out of the water.

Things that are a bit rough:

  * Docs are spread across Reason docs, Bucklescript docs and OCaml docs. A lot features are not documented in Reason, because they're inherited from OCaml. If you would read just the Reason docs you might get the impression that's a pretty small and simple language, but it's actually very powerful. If you're thinking about picking up Reason I definitely recommend you read the RealWorldOCaml book [5].
  * The Reason syntax is a bit weird in some spots. If you make a syntax error the compiler will in most cases just yell `Error: Syntax error` at you which is not really helpful.
  * The ReasonReact API feels a bit alien, probably because it's build on top of the React Class API. I think there a bit some big changes coming to ReasonReact though, so hopefully this will change.

Things that concern me:

  * There's little formal communication about the direction and future of the project. It seems to be mostly Facebook who's behind it, it doesn't feel like a community project at all. Bucklescript seems to be largely a one man show.
  * There have been a handful of Bucklescript and Reason releases that plain broke stuff. Of course this can happen, but it does make me a feel a little uneasy.

All in all I'm definitely positive. There's a lot of potential and hopefully when Reason picks up some more steam it can become more a community project. Be sure to check out the Reason Discord [6], very helpful people there!

[1] https://github.com/OvermindDL1/bucklescript-tea

[2] https://esy.sh/

[3] https://github.com/reasonml-community/bs-react-native

[4] https://github.com/revery-ui/revery

[5] https://dev.realworldocaml.org/

[6] https://discord.gg/reasonml