I am a huge fan of the Patrick O'Brian novels. There are 20 books in the entire series (O'Brian died about 4 years ago).
The problem is the book Master & Commander is Book 1 in the series; The Far Side of the World is Book 10.
So this is going to be a very, very strange movie.
For me, the movie will probably be amusing, but nothing like the books. Unlike, say the Horatio Hornblower books or other Napoleonic-era naval novels, not that much time is spent in battles. As O'Brian once said, "Forrester [who wrote the Hornblower books] wrote great battles; I write everything else." The language of the era, the taste in music, food, and clothing, manners & morals, daily life on the vessels, all this is the purview of O'Brian's novels. Unfortunately, especially given the two trailers I've seen, this will probably be forgotten.
Much more importantly, the O'Brian novels are generally known as the Aubrey-Mataurin novels, after the TWO main characters. Thanks to having Russell Crowe this film is going to be a Star Vehicle concentrating almost entirely on Captain Jack Aubrey, who is a great naval commander, but a man who is nearly hopeless on land. The other major character, Stephen Mataurin, is an Irish-Catalonian physician, natural philosopher, and secret agent, as well as on-again-off-again addict of laudanum; he is also nearly hopeless in understanding the finer points of naval life. It is the interaction between these two characters that makes the novels truly amazing, from their mutual love for music, to their discussion of politics, to their interconnected love lives.
I'm sure this film will have lots of cannons and lots of booming.
It will not be even close to the books, and for that I mourn.