How 'Master and Commander' gets Patrick O'Brian wrong. By Christopher Hitchens:

The summa of O'Brian's genius was the invention of Dr. Stephen Maturin. He is the ship's gifted surgeon, but he is also a scientist, an espionage agent for the Admiralty, a man of part Irish and part Catalan birth—and a revolutionary. He joins the British side, having earlier fought against it, because of his hatred for Bonaparte's betrayal of the principles of 1789—principles that are perfectly obscure to bluff Capt. Jack Aubrey. Any cinematic adaptation of O'Brian must stand or fall by its success in representing this figure. On this the film doesn't even fall, let alone stand. It skips the whole project.