Well, many of the benefits of Rust, but in a simpler and garbage-collected language. Possibly the best language (alongside Haskell) if you need pattern-matching. Not quite as good if you need lots of libraries or interaction with other languages.

It does have a lively ecosystem in some niches. Formal verification is one of them.

For example, https://opam.ocaml.org/packages/why3 is a little marvel of engineering.

Does Haskell have or-patterns yet? Last I checked OCaml still has the lead in pattern matching power :-)