Whoever penned this book did not author the previous ones. The tone, style, structure, and language of ASoF are entirely distinct from the 'corpus Castaneda' (Teachings to AoD) that I have perused at least half a dozen times since 1970. Additionally, there is nothing novel in ASoF, no advancement either in terms of technique, philosophy, history, or spirituality. The book is notable only for its disjointed banality.
So, who wrote what? Evidently, there are two authors here. Did someone else compose the main works to which Castaneda attached his name (with the author's consent) and then, in a frenzy, attempt to write his own material (ASoF)? Or did someone else write ASoF? My hunch is the latter, although the former cannot be discounted. Whichever it may be, ASoF should be regarded with skepticism.