Caspar Henderson’s 21st Century Bestiary is not an encyclopaedia, as some people might expect, but something more in the medieval tradition of bestiaries, mixing information with philosophical and moral comment. It’s interesting, and Henderson’s ideas are well expressed, and I imagine a full colour version of the book must be stunning (my own is the paperback, all in black and white, but I seem to recall seeing a colour edition). It’s definitely not all that scientific, in places, relying on anecdote and going off on tangents into what an organism might have to teach us.
One of Henderson’s major concerns is the environment, and the preservation of Earth’s current biodiversity, for which he makes a good case. Ultimately, if your interest is science, this will probably be unsatisfying: it’s here to demonstrate some of the scope of biodiversity, not to explain it, or even to go very deeply into any one scientific principle (though it touches on plenty).
I do wish it had been better edited — the typos and such are extremely distracting. All in all, it isn’t quite as good as I’d expected from the rave reviews and my quick glance over it in the shop, but it is interesting.