Time and Again by Jack Finney came my way through a recommendation from someone on the internet, where recommendations to be taken seriously are kind of hard to find. Anyway, I have a lot of feelings on it.
One, this book was written in 1970 and it has all the misogynistic and strange casual sexism of its time just built into it. It took me three or four chapters to get used to, but once I got through those three or four chapters (and it took me weeks to do so), for me it was like a little reminder of how far we've come as a society despite the election as Trump and I just rolled with the "nice-looking waitress with a nice bust served us lunch" punches.
Two, the characters are as flat and undeveloped as possible. I can't tell you anything about our narrator except what he did for a living and that he used to serve in the military, both of which are semi-important facts to the actual story. I don't know how he spent his free time, what his childhood was like, or any detail about him that might make him a more sympathetic character. And don't even get me started one the female characters. They might as well be cardboard.
Three, this book takes the existence of time travel as a given. I have gripes about time travel, but this book deals with most of those gripes, so I'm going to let that one go. And the reason I'm going to forgive this novel for all of its many, many faults is the OMG research that Finney must have done to write this. He writes details upon details upon details and makes you think you're there in 1880s NYC. I think he sometimes takes for granted a working knowledge of 1970 NYC, but that seems like unnecessary criticism on my part. Anyway, this was a masterpiece of time travel. The way Finney described not only physical things, but how the air was different, the sounds were different, and the people themselves were different made use of all of the senses and made it a wonderful, immersive reading experience.
So there you have it. It'll take you some time since the thing clocks in a 400 pages and has pretty tense type, but it will be worth it in the end. Go put it on your library list!