I get it, Movies aren't going to be 100% like the books; that's boring. What I don't love is when the story is so different from the book that I have to force myself to watch. Yes, it had its good parts here and there, like how Daniel ignored Luce in the beginning and was mysterious, Also, the fight close to the end between Daniel and Cam was incredible. Apart from that, the movie felt rushed, skipping over lots of important things.
Here's my deep dive with lots of spoilers, and if you don't agree, I don't care.
First, the friendship in the book between Penn and Luce was awesome; in the movie, I didn't see how it worked. The meeting was weird, and there was a lot that the two did together in the book, like going to find digging into Daniels past with finding his file. When Penn died, I didn't feel the same like when she died in the book because of all the changes, honesty when she was on screen like Luce I felt some awdwardness.
Second, too many of the details were revealed too early in the movie, which we found out in the middle or even at the end of the book; that's one of the ways it felt rushed. Also, the cemetery seemed like a big thing in the book because that's where a lot of things happened. In the movie, it doesn't exist.
Third, there's lots left out that if you didn't read the book, the movie won't make a lot of sense, so do that first.
If you enjoyed and loved the book, I would recommend not watching the film