My point is simply attack the theory, not the theorist.
Darwin was a crappy naturalist, a terrible student, and eventually died a materialist. His theory stands or falls on it's merit, not his.
Agreed that Darwin's theory needs to be evaluated on its own merits (not on Darwin's personal qualities or character) and I would go along with Darwin as a mediocre student at best... But the claim that he was a "crappy naturalist" is extraordinary and unaccountable.
DARWIN WAS AN ABSOLUTELY FIRST RATE SCIENTIST, even before and apart from his work on evolution. Good Lord, his monographs on Cirripidae (sp? that is Barnacles) are still standard references to this very day. Granted that works in systematics tend to be longer lived, but this is still remarkable. Also (e.g. in light of the extensive and meticulous dissections involved) indicative of Darwin's strong work ethic and high productivity. He made numerous original discoveries and reorganized the taxonomy of the entire group (with little subsequent change to date). Even before he did much research or was recognized the quality and extent of his collections during the Beagle voyage were remarkable. And still his first original theories (on the formation of coral reefs and atolls) were published, and began to establish his reputation as a geologist, even before he returned!
Then there's the staggering number, extent and care of his experiments. Etc. One could go on and on (even without mentioning evolution).