This book is a great in many ways - as history, as narrative, as travelogue, as social documentary and as Adventure, but I feel that it's probably fair to caution the modern reader that it's written in a style that he or she may not be used to - not flowery, but not spare either. You do get the sense that you're not reading a modern work.
Aside from its other merits, it's great background reading for fans of the Aubrey/Maturin series by Patrick O'Brian, even though it takes place about 20 years after their last published exploits.
Faults? Well, for my taste, there was perhaps a little more sailor jargon than I could take in (the version of the book I read, not this edition, had no diagrams). When he was going into great detail on sails and ropes, I skimmed past some material, but not too much, and was able to pick up the sense of what he was writing about, without necessarily being able to determine the precise difference between two types of sails on the same mast (call me Maturin). Overall, you get the sense that he spent two years in almost unceasing toil, and that life as a sailor in those days was not one that anyone today would envy.
Also, since this was a recount of an actual two year voyage, there was perhaps one or two too many recounts of cruises up and down the coast for those seeking "adventure" reading, but this is an actual historical account, and can't be faulted for some slow pacing - I have no doubt it WAS awfully tedious at times (which the book is not).
However, it has SO many other merits that any patient reader will gain much from it, particularly an authentic, well documented perspective from another time.
So, read the book, but don't think you'll knock it off in one night, or that it'll read like Tom Clancy, or even Mark Twain. Nevertheless, read it anyway, it's well worth it.