This book wasn't what I was looking for.
I wanted a book about time travel, about changing the past and the future, and about some sort of time machine device. That's what I was expecting based on the cover and the description. And yes, I got that, but I also got a lot of ruminations on how time travel works, how it affects the world, and how it affects Dan. This book is full of lots and lots of internal monologue. Not much action. Not even much time travel, when compared to the amount of thinking
that goes on.
A very large portion of that thinking was with respect to sexuality. If that's what you're in the mood for, then yeah, read the book. But it didn't meet my expectations, and that is reflected by my rating.
And now, I have to give you the spoiler tag . . .The main character, Dan, goes backward and forward in time enough, and returns to the same places enough, that he encounters himself a lot. At first that was interesting. Then the the book took a turn that was odd for me, when he has sex with himself. Not just once, mind you; he repeatedly has sex with himself. Seduces younger versions of himself. Has orgies with multiple copies himself.
Then he changes enough about the world that, in at least one variant, he was born as a woman. And you guessed it; he has sex with her. He spends some time thinking about how sex with his female self is different from sex with his male self.
Although I was a tad uncomfortable with the repeated sex-with-himself, I could maybe accept that there might be a natural curiosity there. I would have been fine with it had it not continued on and on and on. It got a little . . . weird.