Let’s put it this way, if you didn’t read the book and just go into it with no prior knowledge, you’ll think it’s a pretty good movie. And that’s fine.
I went with a good friend of mine who liked the book and we would have debates about how good the book is. So we went to the movie together. Every 10 minutes, or when something was changed that clearly was different from the book, I’d hear a very loud sigh. It was actually pretty funny to me, and made me laugh a few more times than the movie did. But I enjoyed it. I’d go see it again with friends.
Without being spoilery, I did have one pretty large gripe with the book, and I thought the movie did a way better job of revising that situation to make it more believable to me. So I’ll give it that.