As someone who had read the book and really liked it, I found the movie as compelling and it excels at additions that are not in the novel such as the last scene which happened after the ending of the book. However, they also removed some good parts from the book, but were offset by visuals and score and the spot on performances of the characters especially Lewis MacDougall (Conor) who nailed his role in the movie. He sure knows how to cry. And that needs pointing out as a lot of kids in movies are sometimes annoying and difficult to watch. Felicity Jones (The Theory of Everything) and Sigourney Weaver (Aliens) who were both Academy Award Best Actress nominees were as good as anyone would expect them to be. And Liam Neeson's voice was the perfect choice for the monster's. Haunting, cold, deep, and soothing. Also, the other thing I found striking was how the book played out as a movie. Aside from a few differences (the adds and minuses), almost everything else is as what the book is. Impactful scenes as how they were narrated and readers imagine them to be and dialogue and life lessons as how they were said in the book were same as in the movie. If you have read and liked the book, then watch this. If you have not, watch it still, as long as you have a heart and know what you're getting into, chances are you'll like this gem of a movie.
