I sometimes get bothered in historical fiction by the author trying too hard. They use far too much slang from the time period, or work in descriptions of the clothes to an eye-rolling degree, or they try to include every famous person in the story who might have known the characters. Well, I didn't think this book was that way. McLain held true to the time period but focused on the important elements--Hadley and Ernest and the way they built their marriage and tore it apart.
I would be careful about whom I would recommend this book to, though. There is some vulgarity and a lot about sex (really, this book could not have been written without the sex). But I thought it was tastefully done and it didn't bother me (and I don't read erotica or anything like that). It's a good thing to be aware of, though, if you're really sensitive to that kind of thing.
All in all, I really enjoyed this book and it made me even more interested in learning about Hemingway.