A quick synopsis. In the first third of the book, Martin puts forth the hypothesis that success and happiness is tied to how optimistic or pessimistic a person is. This trait has three major axes: Pervasiveness, Permanence and Personalisation. He follows up this hypothesis with a test (to measure your own levels). The middle third of the book is mostly a number of case studies, with digressions into the positive use of pessimism and pessimism/optimism in children, and the use of this hypothesis to predict educational, sporting and political results. The last third of the book is about how to learn to be optimistic (and when).
This book is very american-centric. I think it could also have been written in about half the verbiage, and occasionally his meaning is unclear. However, as pop-psychology books go, it is fairly concise, approachable, and rigorous in his treatment of his own hypothesis. He readily admits to changing his ideas in the face of new evidence as his hypothesis has developed over time, a precious thing in this kind of book. It was rather repetitive, but I've been told that I'm unusually sensitive to such things, and I suppose for an audience used to being bombarded every five minutes with mostly-repeated ads it wouldn't even be noticeable. Also, his treatment of conflict within marriage is laughable.
In the positive realm, I think that his hypothesis has something to it. I know that in my own life, I feel happiest when I feel that what I do makes a difference to how I feel - and that in the pits of darkest despair, the overwhelming characteristic was that I felt that there were no solutions, nothing I could do to fix myself, nothing I did was right, etc. I'm sure those feelings are familiar to many people. Seiglman postulates that it was my internal dialogue that was reinforcing these feelings and making my bad situation worse. Optimism here is not about denying that something sucks - it's about defining it as temporary, not about you, and limited in its impact. That is to say, this too will pass, it wasn't your fault, and it won't ruin your entire life.
He provides many examples of different internal (and external) dialogues involved. He suggests keeping a diary of adverse events, beliefs about these events, and consequent actions. Part of solving any problem is figuring out there is a problem. To break the constant negative self-talk, he suggests using distraction as a first aid measure, or disputation as a longer term curative. I do think his examples are somewhat shallow; I certainly put up more of a fight with myself than he seems to think should be the case. But then, I'm a champion at holding opinions, and I'm very good at argument. Most people aren't quite so strongly trained as I am.
Today, I think, his techniques have been expanded and incorporated into Cognitive Behaviour Therapy and Neuro-Linguistic Programming. After all, this book was written in 1990, and a lot has changed in the world since then. Overall, it's a good book for learning where modern techniques started, but it has significant gaps, and is definitely pop science. I found it interesting, but for dealing with my current issues would go for something significantly more recent and more thorough.