Currently Reading
I've avoided Castaneda because I've read that the books were largely shown to be fictitious. Daskalos (as the Magus is called) is much more obscure of a figure, as far as I can tell, so there's less mythology surrounding him. I'm not aware of Markides' account as having been called into question. He's an anthropologist and seems trustworthy. You can even find interviews with Daskalos on youtube.
His ideas are a marriage of Christian mysticism and Hinduism, in a nutshell, which automatically attracted me. If you read mystic literature across disciplines, and then read this account, it's basically all the same thing. It's the Perennial Philosophy.