Great book in so many ways, most of which I am sure will have been covered by other reviewers, so I'm just going to go ahead and get this off my chest:
Ok Charlie, I get it, it's a metaphor. Your metaphor is about as subtle as a breeze block across the head, do you really then need to spend the next paragraph explaining exactlty what it means? I'm not a complete imbecile!
There, I did it. I can relax now.