This book is based on Cognitive Behavioural Therapy (CBT), which basically sets out to help you become aware of where you are thinking unrealistically (or just plain wrongly), and to replace these thoughts with helpful and more realistic ones.
I was really scared for a fair while that this book wouldn't help me, but actually it has, and loads. By about half-way through, I was daring to believe people actually loved me, I was approaching groups of people and joining in with the conversation, and being open about who I am - and starting to enjoy doing so, and not assuming everyone disliked me.
However, you need to know that this book is sometimes difficult to read, and to change will be hard. This is not a book that you "read". This is a book where you read a section, then you have to do the exercise - sometimes daily, for a couple of weeks - more like a "workbook". If you read this book cover-to-cover, it will have little discernable effect on your life. However, if you put the time in, you will notice real changes fairly soon.
I have to confess by being really confused and a little upset for some of the people who gave this very negative reviews - it doesn't advocate simplistically thinking "positively" in the face of all the evidence. To the contrary, it helps you set up experiements to discover what the truth actually is, and what you can do about it, and helps you examine the evidence from your experiments in a more rational way.
Finally, you can only do this if you *want* to change - yes, this book is aobut changing quite fundamental thoughts you may have about yourself, which you may have clung to for years like a safety blanket and not want to believe actually aren't true. And it will be hard! However, for me it's been really worthwhile. Good luck!!