Worth stopping by the discord [0], it's grown quite a bit and so has the (editor/build/etc.) tooling. There's no Apollo/Relay story yet (that's the biggest missing piece for me on the client side), but everything else is pretty decent!
It was a bit tough to get tooling set up and it doesn't work on Windows, but on Mac (and Linux I assume) it's amazing. Better Intellisense support in VSCode than Typescript!
It is very new though, and I haven't got a complete grip of JS FFI with Reason.
Hey a quick question — which Flow extension are you using? There's the official one called "Flow Language Support" and another one called vscode-flow-ide.
UPD: sorry, I just realized you were talking about Reason, never mind.
[0] - https://discordapp.com/invite/reasonml