This was recommended by someone that I trust, but I really didn't like it. It is overlong and the writing is not that good. Fitzroy seems to have been an interesting character who was badly treated and under-appreciated, but this book makes him about to be something like a saint. His hunches are always right, he is always on the right side of every argument, and his thoughts are almost always honourable. His main character flaw - his terrible temper and his bipolar disorder - is presented as something entirely external to him. I don't want to diminish the illness, but the way it is described means that it is nothing to do with Fitzroy's self. The book is also entirely sympathetic to Fitzroy's politics - he is a reactionary Tory paternalist. Everyone else (including other Tories) are presented as cynical and corrupt, especially the Liberals and the Radicals. The Chartists get a walk-on part as a ravening mob. Liberal factory owners are hypocrites. Only Tory landowners have the real interests of the common people at heart (I bet David Cameron would love this book). Only believing Christians who think that savages have immortal souls that can be saved for God are not racists. As a naval officer Fitzroy maintains iron discipline (including just the one flogging) but his men respect him for it.
Perhaps the worst thing about the book is the portrayal of Darwin, who comes across as vain, pompous, cowardly, unreliable, snobbish and racist (a proto-social Darwinist, looking forward to the extermination of inferior races). The book really is a hatchet job here. No petty thought of Darwin's is too trivial to be described; imagine a biography of Martin Luther King that recorded his thoughts about the footwear of the people he met. Now I am not a Darwin scholar, but I have read his account of The Voyage of the Beagle, and he comes across there as a really great guy - someone I'd happily have spent time with. Of course that's his account and necessarily biased, but even so - the things in which he takes pleasure, and the things that he hates (including racism and slavery) suggest to me that he was not much like the Darwin of this book.
I am bemused by all the people who think that this book is so great; what else do they read?