He did some original work, stuff that has changed how biologists approach several sub-fields, but most of his books are popularizing science, at least the ones that are more concerned with biology than gods.

Selfish Gene is particularly useful, and if it sounds old hat, it is akin to the director (producer?) of Starship Troopers statement that he didn't use power armor because it was used everywhere in SF. (Elsewhere he has some extended work and clarification for the first half of that book. I've not read the newer edition to see if he has updated it to include the new stuff or not.)