I think we all agree that "non-ordinary" states of consciousness exist. Yay for agreeing.
I'm sure the book with the long title you linked to is a solid psychedelic reference and scientific companion, with a little adventure thrown in.
Castaneda was heavy on the adventure. "A Separate Reality" is hilarious and insightful. Stories can pass knowledge and Castaneda certainly supplied stories. The books are like psychedelic Mexican westerns, an average westerner protagonist on a quest to match the great Sorcerer's tripping skills and make new inorganic friends.
How could you possibly cast a dark shadow over that synopsis? :-)
That some became disciples of the books is no surprise, but Castaneda's words did the heavy lifting.
Romanticizing the word 'Ayahuasca' is annoying. It's just a name for an organic substance. The "mother" thing is SYMBOLIC guys - symbolism was HUGE way back in native times. Symbols and static icons also act as a safety net for the chaotic nature of our own minds under the influence, and the right symbols can turn a bad trip good.
The key here very much being "under the influence". That's chemical influence, on your very sensitive brain, which has a natural chemical balance that you are disrupting. No wonder dream states emerge while you're awake.
Seriously.. it's completely the wrong track to mix belief in intelligent other-worldly ghosts that say hi during your trip, and rigorous scientific psychedelics.
I would like to visit Brazil one day, I'll never say never. Does the Ayahuasca jungle-cafe serve peyote?