Having just finished the book & ending it off by watching the movie to it, I’d say that the 2 of them compliment each other. Having read the book just before puts a bit more meaning into the movie.
Nevertheless, I can’t say that I have enjoyed the book. Yes, there were some parts which managed to transport you into a relaxed summertime Italian setting, but the story was just too banal for my liking. In the worst parts, the main character even reminded me of a bit of a lighter version of an obsessed Anastasia from 50 Shades of Grey.
Though the style & the way the book was written flowed well & easily, I couldn’t have cared less about the characters.
So if you happen to come across the book and feel like you HAVE to read it, because you heard so much about the movie, just don’t. Spare yourself the time & watch the movie instead & marvel at Timothée Chalamet’s acting skills.