I have read it because it was recommended to me as a way to raise emotional intelligence. You know, that thing that is more important that 'standard' intelligence measured by IQ tests.
First I will admit that I haven't done all of exercises in the book. I barely started (and hope to have something similar at work as they had at google). But this book was insightful.
Most important thing for me was learning about mindfulness and meta-attention. Of course it helps that all of this is backed by science ;). Meta-attention is being aware when your attention wanders off. Think about how useful it can be. You are trying to do some work but get curried away by facebook/email notification. Best thing is that it can be trained with only 2 minutes a day. The only thing you do is you try to focus on your breath. When your mind wanders it's not failure. It's most important part of exercise. You train bringing your attention back to breath. There is great metaphor for that. It's like riding a bike. When you are beginning you fall a lot to left or right. With time you can adjust a bit a ride a bit longer. When you can ride you are adjusting all the time to left or right. It's just very subtle so it looks like riding straight. The same goes with attention. Your mind wanders and you bring it back. If you train with something like breath to master attention you can bring attention back in the moment your mind would wander so it would look like constant attention - focus and hopefully 'flow'.
It's just one example from the book. Latter chapters bring much more sophisticated techniques that will help you understand other people, better know the feelings and values of others.
For me it was challenging to read this book. Language used is often abstract. Add to this that I'm not feeling strong in emotional intelligence and it was tough from time to time.