If a great OCaml guru/teacher wrote a great book, I'm sure it would have great sales on Amazon (I'd buy it :)
 
You may want to read this book :
http://caml.inria.fr/pub/docs/oreilly-book/html/index.html

It is the english translation of the french book "Développement d'applications avec Objective Caml":
http://www.pps.jussieu.fr/Livres/ora/DA-OCAML/index.html
http://www.amazon.fr/exec/obidos/ASIN/2841771210