You should definitely read the book. It's a pretty easy story to digest, and there are a lot of little things they left out or rushed for the sake of the movie being a movie. I thought the movie was fine. Not the best way to adapt the story, but it was a good try. It was at least fun to see Tom Cruise as kind of a bitch for a little while instead of being the big strong lead character through the entire movie.
Also, the book ending is WAY cooler than the movie ending, in my opinion. I would've loved to see that ending go down instead.