I definitely had the same positive experience with using OCaml/Reason at my job as well. There's so much power in being able to accurately represent the data model in the type system.
Besides that, the compiler becomes a partner in coding. - Refactoring things is no longer something I avoid, because the compiler will point out any unexpected places that interact with a given piece of code. - I can code for an hour without loading the app, and be reasonably certain that the code I'm writing will be more or less be correct. Overall, I feel like the compiler does the double-checking and second-guessing that I was always doing in the back of my head, which gives some peace of mind and frees me up to focus on the actual task.