Having asked everyone else to reflect on the Origin and post their reflections, it's only fair that I should do so too.
I enjoyed the book tremendously, and I'm glad I no longer have to embarrass myself by admitting I hadn't read it. I'm even secretly proud of having read the first edition, when most other people have read the sixth. It's a bit like being able to boast that you saw the original version of a great foreign film rather than the Hollywood remake.
I've come away hugely impressed with Darwin's prescience. It's just stunning (even a little scary) how many modern ideas in ecology and evolution are already there in Darwin, and how they all fit together in his mind in pretty much the same way they do for us today. And his error rate is so low--that surprised me. I expected to see that Darwin would have a firm grasp of the core idea of evolution by natural selection, and he does. But I expected that his thoughts on peripheral details and specific examples would often be somewhat wonky. They're mostly not. It's rare that you catch Darwin failing to extend an idea to its logical conclusion (as in his failure to see that what we now call antagonistic pleiotropy can explain vestigial organs in cave dwellers as well as in parasites), or just proposing a strange-sounding hypothesis (as in his explanation for brood parasitism in birds). I'm sure some of this is luck, but I don't see how all of it could be. Darwin's just too right, too often. As the saying goes, it's best to be good and lucky. And it's extraordinary that he managed to see all this without knowing anything about transmission genetics or developmental biology. Even Wallace, who had the same basic idea, never came close to working out all its implications or marshaling all the various lines of evidence given by Darwin.
Ironically, the one area where Darwin's reasoning disappoints me a bit is in the explanation of the origin of species. Darwin's terrific on the origin of adaptation, on how you get Design without a Designer. And he's terrific on the evidence for evolution, and on how his theory ties together a huge body of apparently-disparate facts in fields as different as embryology and biogeography. But as I've described in another post, I don't think he had a sufficiently strong appreciation for how selection pressures could vary from place to place, and I think this is what led him to propose the Principle of Divergence. This principle is clearly crucial to his understanding of how natural selection leads to speciation, but it doesn't stand up to empirical or conceptual scrutiny, and I think its flaws could've been seen even at the time.
I'm also impressed with Darwin the fact hound. He's determined to get things exactly right, even if that means rejecting an idea he'd worked his butt off on for years. I'd like to read some of his letters to get a sense of how much of this impression is just a rhetorical pose. Surely he wished and hoped that evolution by natural selection was The Answer, right? But how could he wish that and at the same time put that wish to one side and truly take seriously all possible criticisms of his idea? My experience is that science proceeds on a sort of adversarial model (what philosopher David Hull called "science as a selection process"), whereby competing theories each have their advocates and the court of scientific opinion sits in judgment, with peer review "selecting" for the best theories. Of course, I do try to criticize my own ideas, if only because I worry that if I don't I'll get trashed by peer reviewers, and I think other scientists do as well. But I'm not sure that Darwin's self-critical approach is a dominant one.
Closely associated with Darwin the fact hound is Darwin the polymath. The age of specialization began before Darwin (Leibnitz was said to be the last man who was an expert in every field of human knowledge), but it hadn't yet gotten to the point where one couldn't be expert in all the fields Darwin draws on: geology, paleontology, ecology, etc. I flatter myself to think I'm slightly more widely read than my fellow community ecologists, at least in certain fields. But I'm absolutely a dilettante compared to Darwin.
Going in, I had no idea that Darwin took "special creation" as a serious alternative hypothesis, or that his argument against it isn't so much that it's falsified by the data as that it explains and unifies nothing. This is rather different from the arguments you see deployed against various versions of creationism today. And of course, those arguments are only deployed in the context of political debates today. It's interesting to be transported to a time when creationism really was a viable scientific hypothesis.
Darwin's reticence on the implications of his theory for people (and God) strikes me as very wise. It's a rational choice for someone like Darwin, who always wants to be completely sure of his ground. But it strikes me as an ethical choice, too. It shows respect for those with other, possibly conflicting ideas. Richard Dawkins has many virtues, but one of his vices is failure to take seriously alternative points of view with which he disagrees. Dawkins doesn't suffer fools gladly, but he also gives the distinct impression that he has all the answers and that anyone who disagrees with him is foolish.
So if I admired Darwin before (and I did), he's one of my heroes now. Evolutionary biologists are sometimes accused of "worshiping" Darwin, as if he were a god himself (this is the "Darwin the Myth" of Mott Greene's recent lecture). I can see why now, and I couldn't before.