This was a really fun book, and much more enjoyable than most historical fiction - mostly because for once there isn't a boring romance swallowing up the entire narrative, what a time to be alive! The massive amounts of research that must have gone into this book are really evident (sometimes a little too evident) and from what I can tell it does a really good job transporting the reader into the mindset and the overall feel of this period in the British Marine. The two main characters are charming and sympathetic, both eccentric in their own right but not so much that it becomes their only character trait. Their friendship is heartwarming and genuine while still playing by the rules of the time - a lot of historical novels do this thing where they resort to modern social behaviour to communicate their central relationship, but O'Brian trusts his readers to get it, which I really appreciated.
However, this book loses a star each for:
1) the nautical talk. It's just... I know this book is set on a boat. I know that's the whole point. But sometimes, there will be half a page devoted to the description of which sail was set and what effect this has on which part of the ship and what commands are given and... Maybe this is fascinating for someone with more interest in nautical stuff, but I just wound up skipping entire passages and probably missing a lot of the intricacies because it just exhausted me. (There is a glossary at the back, which I didn't realise because I was reading the book on an e-reader, but personally, I just don't appreciate it when you keep having to flick to the back just to understand what the author is talking about.)
2) the episodic nature of the story. In and of itself, that's not necessarily a bad thing, but I think this book would have really benefited from some kind of overarching plot. Going in, I thought that the growing friendship between the captain and his new ship doctor would have this function, but they got on like a house on fire, so there wasn't a lot of suspense to be found here. There was another plot point involving Jack, Stephen and the ship's first mate which I thought would have more of an impact, but that didn't really go anywhere after the initial escalations. And other than that... the book starts at a pretty logical point - the meeting of our main characters - and then you follow the exploits of the ship on one mission, a squirmish, then another, a new mission, then another, and a lot of these individual episodes are quite exciting and are resolved quite satisfyingly. All of it is connected insofar as it's all the same war - but that's it. The book could have ended at at least six different points and it wouldn't have made any more or less sense than where it actually ends. I'm sure that doesn't bother some people, but it kind of frustrated me. While I was enjoying myself a lot reading the book, I couldn't tell where it was going at all. And even now that I've finished it I couldn't say what the point of telling this story was for its narrator.