I've always felt that Isaac Asimov writes brilliant science fiction with boring characters. I love a good time travel story, mostly to see what this author's take on the usual time travel paradoxes will be. Anyone who writes about agents changing history has to explain how they deal with things like the Grandfather Paradox, meeting earlier or later versions of yourself, and so on. There are a handful of well-known ways to deal with these issues (alternate timelines, a deterministic universe, special laws of temporal physics, etc.) and Asimov is rather inventive in using several of them at once.
Although The End of Eternity
is brilliant in its construction of a civilization of time travelers and all the history and technology that goes into their society and the way they meddle with time, his protagonists are basically a bunch of whiny geeks who've never kissed a girl and act like highly-educated chimpanzees fighting for the highest branch in the treehouse. Asimov's vision of a civilization that spans millions of years and thousands of realities doesn't include a single one where women become scientists and engineers and might join the Eternals' boys' club. The entire plot hinges on not one but two high-ranking Eternals who decide they are willing to throw all of reality into danger for the chance to get laid. I know Asimov was a nerd and he wrote this in the 1950s, but he still could have done better. It's like the idea of women as anything but sex objects to be coveted or to seduce men off the path of Righteous Scientific Objectivity just never occurred to him. So naturally when a girl shows up (the only female character in the entire book), she must spell T-R-O-U-B-L-E, and in this case, the end of Eternity.
I enjoyed the story, but Asimov has never been my favorite among the Grand Old Masters of science fiction; there is something just a little too cold and calculating in all of his stories. For the ideas and the plot twists, this is a fun book with a great premise, but don't expect Asimov to wow you with his nuanced grasp of human relationships. His characters are wire dummies to hang a story on.