The issue is quite simply that the world is going to run out of energy in the next 20 odd years, and there is nothing we can do to stop it.
I'm about half way through it at the moment, and it's a scary read.
I think the most frightening thing about it is that he doesn't sound like a fanatic, and comes across as a well-informed, intelligent and rational man just presenting the facts. It's all basic, common sense applied to the oil crisis, and it terrifies me.
Go there and download the pdf of the book, and give it a read, and once you have read it tell me your opinion. I know I am easily swayed at times, so I wouldn't mind some other peoples opinions.
Edit: Well, I've finished the book. In the second half of the book he gets into a lot of doom and gloom scenario's, but it still all seems like a logical extrapolation of facts. It still scares me.