Really! This is sage advice. Don’t ever judge a book by the movie adaption of it. This is especially true of actual novel-length works since they contain far too much content for a single movie.
Oh! And yes, this holds true in both directions. If you liked the movie, you may still dislike the book, or even hate it – e.g., I know of very, very few people who enjoyed Starship Troopers as a movie who also didn’t hate Heinlein’s actual 1959 novel.