It is much more like JavaScript than ocaml and so you get a familiar language but one which benefits from all the cool things that ocaml can do.
I only saw rather simple typing examples, which didn't seem much different from what TypeScript can do.
On the other hand I read often that ocaml doesn't have runtime errors, which I certainly get with TypeScript.
Of course the rest of the book is a great read too if you're so inclined.