I wrote briefly about this book in my "Self Help" blog.
I will say again that I am not a huge fan of NLP and I believe it takes more than simply finding the positive or "flipping it" when you have a mental health issue but this book is a very good place to start. There are some great reviews on Amazon for this book.
As I mentioned, NLP is not really my thing but this book humanises the whole idea. It teaches you how to take the control back in your chaotic life. It's not about mental health at all but it is very useful in all aspects of life. I initially came to this book after a rather messy break-up and I have found myself coming back to it time and time again to help keep myself positive.
Take a look at Michael Heppell's website and Twitter feed for further information.