I can't recommend this highly enough. Jason Blume is clearly a man who really, really understands songwriting, and not just how to do it, but how to explain it. His writing style inspires a very thoughtful read, and his advice often gives you ideas of your own. Some of the more technical topics are in need of an update (he doesn't really give fair mention to the amazing possibilities of modern home studios, for instance) But if you are trying to reach untapped potential as a songwriter, then this book will surely stay in your collection as long as you live. I have read it cover to cover twice, and still can open up a random page and feel enlightened.
Jason Blume was at one point living off of cat-food. Whatever he has achieved (that's quite a lot), he has achieved from the ground up. I hope that one day his book can help me to say the same. Definitely worth five stars.