This is the fourth of the Aubrey/Maturin series. It's the most novel-like of the series so far, which thus far has read more like a long biography than a series of novels. The novel's central conflict is the English campaign to take two islands in the Indian Ocean away from France, and the narrative remains with this campaign throughout. Some of the previous books have stuck with a theme, as alltoseek pointed out -- Master and Commandercovers Aubrey's command of the sloop Sophie, and H.M.S. Surprise mostly covers one mission -- but neither book has a central conflict that runs through it.
There's quite a lot of naval warfare in The Mauritius Command. I still don't really follow the fighting, but I am coming to like it, though I can hardly explain why.
I found the novel bittersweet. I fear that the weight of life and years has cast a permanent pall over the outsized good-natured puppy that was Jack Aubrey in Master and Commander. I mean, he's still good-natured and he's pretty upbeat for most of the story. But I miss his terrible, terrible jokes, and his unfathomable enjoyment of them. I suppose even puppies have to grow up eventually. But still.