I've not had a chance to read the book (too many other things I'd rather read first), but I did see the movie, which I found to be pretty worthless. What bothered me most about it, though, was that the child was so unrealistic for a child of that age raised in a post-apoc wasteland. The only excuses for a child with that little sense/few skills is that the parents utterly babied it and prevented it from learning the importance of being quiet, careful, and knowing how to scrounge, etc, or the child is actually mentally/developmentally handicapped and can't recognize those dangers. (So the child either has to be handicapped or the father is a horrible parent.) The child in the movie looks to be somewhere between 8 and 12, and yet seems to have no understanding of the danger he faces. Children of that age, when raised in a dangerous world, can easily be much more mature. Children in war torn countries or more agrarian lifestyles are easily more useful. The movie's kid is a walking plot device to get the father into trouble.

So, flaw of the movie or of the book too?