The rating is mostly for importance. This is probably the most important (non-fiction) book of the 19th century, evne if it isn't the best. I don't really know what life would have been like for someone like me before this but I can imagine it would have been a tad more frustrating. So thanks Charles. Darwin is hardly the most engaging writer on biology (I'll take Konrad Lorenz any day of the week) but that isn't really the point. And there are flaws: he avoids answering certain foreseen criticisms (supposedly he had a word count to stick to, but who knows), and he personifies "natural selection" all too much. Of course we know that it is just the name for a process that happens naturally, rather than a thing that picks and chooses traits. But then he was writing in a certain time and that can't be helped. Flaws aside, it's imprtance cannot be understated, since it's hard to imagine most human- and animal-centric science since happening without it.