After spending a fortune on Osteopath's and Chiropractors and getting into heavy debt trying to get my back problem (a sprained left sacroiliac joint along with a slightly swollen disc at L4-L5) resolved, this book (recommended by my own Osteopath!) helped me achieve more satisfactory lasting relief than any treatment ever did.
Gone are the days when my back would sieze up leaving me unable to move and I haven't had (or needed) a single treatment since improving my posture using the advice from this book. It's been 5 years now since I read this book and I haven't had to take a single day off due to any sort of relapse of my back problem. And after being off for nearly 4 months previously that's a phenominal result.
And to be honest I didn't really even do any of the exercises recommended in the book, but I wouldn't advise doing that as the exercises are designed to help you retain mobility and full range of movement while your back heals by reducing the formation of unflexible scar tissue.