Many people assume that Darwin's initial account of natural selection is so out of date that it is to be avoided in favour of more recent text books of evolutionary theory. While it is true that huge gains have been made in the one and a half centuries since the first publication of "The Origin", there is nothing in this work which is wrong. Darwin was too good a scientist and too cautious.
Some claim that Darwin admitted of the possibility of Lamarkian mechanisms. They have not read the original. Darwin knew nothing of the molecular basis of genetics, but knew that natural selection did not need a Lamarkian mechanism. He simply did not rule it out, although he found it improbable. Everything that is stated in this great classic is as true today as it was at the time of first publication.
It is also said that Charles Darwin was a lesser intellectual when compared to most other great names of science; that he was a plodder, a naturalist, a sort of gentleman stamp collector who pressed flowers into his books and barely a scientist in the contemporary sense. This is nonsense. Darwin was one of the giants of rigorous systematic thinking; the kind of rigorous thinking and critical attitude that asks the right questions and provides the capacity to answer them. Let me buttress this claim with one example.
At the end of chapter six Darwin noted that the theory of natural selection could not account for structures or behaviors found in one species that exist solely for the benefit of another unrelated species. In setting out the theoretical terms for the refutation of the theory in this way, he anticipated Karl Popper, that analytical non-nonsense philosopher of science, by more than a century.
I recommend you read this book with an attentive curious analytical mind. You will find yourself walking in the footsteps of an intellectual giant.