Listened to the audiobook version of the book some months ago. I don’t remember all the details but I’d say the movie was great adaptation.
I’d assume some who left bad reviews expecting it to be a comedy haven’t read (or listened to) the book. It does have some actors that are typically seen in more comedic movies. And not all moments are 100% serious in this book/movie, buts that’s because it starts off with a group of childhood friends hanging out at a cabin joking around.
Really loved the book and enjoyed the movie. Cool to see some of what I pictured in my head as I heard the story, be portrayed pretty closely with the movie.