I'm also half-way through reading it, and it's about eating intuitively and listening to your body, rather than being on a diet as such. There's no restriction on the foods that you eat, but you only eat until you are full. It also talks about the 'famine response' that people have when they are on a diet and how they start off okay, but then feel ravenous after days or weeks.
It's an interesting book and sort of along the 'dieting makes you fat' thought. It more or less says that if you are ravenous, our body is telling us to eat and that's exactly what we should do, otherwise we store up the fat we have because our body behaves as if we are in a famine. It made sense to me.
That was my reading of it anyway.