Also worth reading the follow up - OCaml: What You Gain [1] and the overall retrospective [2]. If you search HN for the titles you can find discussions about those. The author will be also be speaking at OCaml 2014 this year [3].

[1] http://roscidus.com/blog/blog/2014/02/13/ocaml-what-you-gain...

[2] http://roscidus.com/blog/blog/2014/06/06/python-to-ocaml-ret...

[3] http://ocaml.org/meetings/ocaml/2014/program.html