Damasio starts by looking at those such as Phineas Gage who suffered a terrible accident in 1848 which destroyed part of his brain. His reasoning seemed to survive, it was his emotional response which was affected, but he became unable to continue at his job or his previous life. Damasio also considers anosognosics, typically stroke patients who are paralysed in part of their body but deny the fact. The evidence is plainly there, but their feeling, influenced by the damage to their brain. overrides it. The book goes on to look at the way the connections in the brain work, explaining, for instance why a 'put on' smile is subtly different from a real smile. As well as arguing for the importance of emotion, Damasio also stresses that not everything is happening in the brain. When we experience an emotion the brain sends signals to different parts of the body, and the signals it gets in return become part of the emotion we feel.
So who should read this book. I'm not really convinced of its suitability for a general readership. It's not that Damasio uses technical language, its just that his style isn't particularly easy to read. If, though, you are interested in the emotions and the nature of thought then you will find it a valuable read.