I'm not generally a fan of science fiction. I'll only read it if someone who knows me well really insists I'll enjoy something, or, in this case, because it was written by an author I really like. If not for who wrote it, I'd have missed out on this one.
I'm going to try to keep the spoilers to a minimum, and avoid major ones completely. So, the premise of this story is a man with a terminal illness builds a time machine to travel to the future, leaving his life behind, in hope of being cured and starting anew. In the future, he finds a world in which human beings are engineered. They all look identical, and the sexes have been eliminated.
I enjoyed the concept, finding it original, but also making sense to me. The ramifications of everyone looking the same are addressed beautifully. There are frightening questions like how you can be sure who you know is who you think they are, when everyone is truly identical. And other concerns, like how one establishes individuality in such a world.
Concepts of theology, love, homosexuality, and other politics are explored. But what really got to me in here were the characters. I particularly liked Pax. I felt rather deeply attached to that character, despite being fictional. I always consider this a major win, when an author can do that to me.
The writing sometimes bordered a little bit on saccharine, which is absolutely fine with me, but may not be to everyone's taste.
The only very minor criticism I had was that I felt like there was some expressions in it that were anachronistic. One that I recall was, "Real mature." I can suspend my disbelief regarding a man building and successfully using a time machine, but I'm not so sure modern slang would've hung around for the number of years that went by. Still, this didn't take away at all from my enjoyment. And there was a little bit of new slang introduced that I did really like.
Ultimately, read this for the characters. That's what I enjoyed the most. And it's just a good story. Enjoy.