The book is available on Leanpub (PDF, EPub and Mobi).
It's not finished, but there's already enough content to help explorers and practitioners.
Paper version will follow
The book is still under active writing, on leanpub.
Is it complete?
No. There's still fixmes and incomplete chapters.
Is it worth the price?
Big Picture Mechanics are pretty much covered, while Process Design and Software Design are still fare from complete. However, the price is reflecting the completion state.