I attended the talk Yaron gave so I have a little context - OCaml is definitely, definitely worth it, and I feel like I have a decent grasp of the language after only 3 weeks of working with it, to the point that I can make useful, large programs.
I've learnt Haskell in the past and it was slow primarily because Learn You a Haskell is I think poorly written.
Read Yaron's book Real World OCaml. It's great.