Take at face value = bad. Absorb what's useful in it = good. Read as part of New Thought history = good, if you want to understand the evolution of certain branches of occulture, including the book marketing (which is so important to think critically about). Read as part of the history of western esotericism = very good. Get angry because it doesn't contain unimpeachable positivistic assertions about the nature of reality that can put you at ease (and maybe get even angrier because you let yourself believe such unimpeachable assertions were readily available for $10 on Kindle) = probably not so good.
Apart from reacting to new age pop-occultism and its superficiality, I think serious occultists tend to dislike books like this—especially occult books that try to borrow authory from previous eras or Ye Ancient Mysteries—because they're in search of the stone of the wise. In other words, they're engaging in a kind of ontological reductionism, trying to determine a minimum state or presence that will serve as some kind of sturdy, reliable foundation for their beliefs.
They get pissed off when an author says, "Here are the foundational principles of reality" and the foundation proves to be very shaky, built on half-truths, and historically associated with a lot of new-age frippery. The same angry occult seekers tend to be confirmed modernists in love with Crowley (who someone once called "the Picasso of magic"). They often criticize chaos magic and postmodern theory because the anti-foundational (Nietzschean) instability that these philosophies generate can seem like unreliable sophistry and it causes them a lot of insecurity.
We want good, solid ground beneath our feet. We don't want "nothing is true; everything is permitted" or "truth is a construct emerging from discursive tensions." Sure, pal. In the meantime, let me go do the Star Ruby in peace. I'll be in the basement re-reading A Moveable Feast if you need me.