This book reminded me of Ursula K Le Guin's writing. Something about the descriptions, the pacing, the plotting, the characters, echoed that author's mode and style. Not that I think Wild Seed is derivative in any way - it is one of the most unique stories I've come across recently - merely that the author happened to have similar style and preferences to Le Guin. Also like Le Guin, Butler takes a fairly common concept - that of immortals interacting with mortals - and follows through on it in a way that makes it compelling and original. This is, in many ways, what I've always wanted to see in a book that tackles that concept.
I love classic, hard science fiction (we've talked about the difference between hard and soft science fiction before). Verne, Wells, Asimov: I've read most of what they wrote. These stories, exploring scientifically rigorous possibilities and ideas, hold a unique place in the huge volume of work classified as science fiction. To use the MICE quotient, these are idea stories, through and through. I'd heard about Ringworld in a few different places, and decided that this was something I needed to read.