This note was last modified Wednesday, 21-May-2014 19:35:53 PDT.
This note contains spoilers for the series.
I was very late finding these; they started appearing in 1969, before I'd even discovered the Hornblower books, but I didn't find them until Mike Ford pointed them out in the late 1980s. After that I watched intently for new books to appear (mostly at Uncle Edgar's Mystery Bookstore, which carried wooden navy books as a sideline; at the time I was watching for many authors in that part of the store, O'Brian and Ellis Peters and Peter O'Donnell and Anthony Price).
I'd call them the best of their genre—that being books about naval life in the age of sail. The Dudley Pope books are excellent, and I do really like C.S. Forester's Hornblower saga, but these are better. As to Alexander Kent's "hero" Richard Bolitho, the less said the better.
It seems to me that the characters are more truly of their period than many of the protagonists of historical novels. It's a fine line to walk, you have to get the reader to understand the character's motivations, and you generally want actual empathy with the character, but lots of aspects of period behavior are unpleasant or shocking to a modern audience.
They've been described as the counterparts to the Jane Austen novels. They're set in the same period, and this is what the men who were away in the Navy were doing; Austen wrote about what the people at home were doing.
There are 21 of them. Well, 20 and a half; there was a partial manuscript when O'Brian died, which was eventually published simply as 21.