O'Brian's magnificent gift is placing you, gently but precisely, within the world of early-nineteenth-century England. No cultural relationship is spared: men and women, rich and poor, the learned and the ignorant, the military man and the scientist. How do they talk? How do they relate? How do they think? O'Brian is not didactic. He is just overpoweringly learned. You feel like you are there. And you benefit from his erudition with the greatest pleasure.
And then, over and over, he takes these people who you have grown to know so well and sticks them in Egypt, or Malaysia, or shipwrecked on a remote island in the Pacific. And those people, those representing the foreign, are rendered equally real. Magical.
His books are a jewel of English literature.
Start with Master and Commander. Don't despair, though; though it is the first book, he did not, at that point, intend to write a series. Finish the second book, Post Captain, and delight in being swept away.*
Don't take my word for it; Mamet thinks O'Brian is incredible too (Mamet is brilliant):
His Aubrey-Maturin series, 20 novels of the Royal Navy in the Napoleonic Wars, is a masterpiece. It will outlive most of today's putative literary gems as Sherlock Holmes has outlived Bulwer-Lytton, as Mark Twain has outlived Charles Reade. God bless the straightforward writer, and God bless those with the ability to amuse, provoke, surprise, shock, appall.*They're cheap on Amazon.
The purpose of literature is to Delight. To create or endorse the Scholastic is a craven desire. It may yield a low-level self-satisfaction, but how can this compare with our joy at great, generous writing? With our joy of discovery of worth in the simple and straightforward? Is this Jingoism? The use of the term's a wish to side with the powerful, the Curator, the Editor. The schoolmaster's bad enough in the schoolroom; I prefer to keep him out of my bookshelf.