This novel came out in 2010, and was released as a movie in 2013: what a fast turn around! In my experiences, I've noticed that usually its 10+ years before novels gain enough recognition to be turner into movies, but because of this books instant popularity, and fitting into the popular theme of zombies, it was made into a movie really quickly, I guess.
Today I'm going to be a fan of the movie over the book!
The book had a few really difficult pieces for me that I couldn't get past, and the movie improved on those in a way that made the story more impacting.
The book keeps us in R's head in the beginning for too long: we are stuck with his mumbling and confusion and are unable to really get past this until Julie enters the story. In the movie, the story begins at the time R and Julie meet, and thus it has a much faster progression. Sometimes I get mad at movies for going too quickly, but in this case, the story was improved by us being thrown right into the mix.
Another aspect of the movie that I really enjoyed was the representation of the Bonies. "Bonies," the greater evil in comparison to zombies or humans, are present in the book, but their presence is almost minimal, and doesn't provide any huge motivation to action. In the movie, this was revamped: the Bonies become a common enemy to both the humans and the zombies, and ultimately become a way that they can relate and begin to make amends between each other. This characterization really added to the action and suspense of the story, and I thought it was a great choice by the director.
I also really hate when books spend too much time using a song's lyrics, written in to the novel, to explain how a character is feeling: there is a reason books are used, and there is a reason movies are used. Lyrics, musical sound and related things often do not translate well into text, so I really thought that these song choices were only really effective in the movie.
Overall, the movie was a lot better than the book for me, and I don't think you need to experience both. The movie gives you the story that is stronger, and is much more enjoyable overall!