I've heard generally negative things about it from the people who did read it. When I tried to flip through the book myself, it seemed poorly organized, devoid of some core concepts or adequate explanations, and contained mnemonics that were absolutely worthless (Willis the spider? GTFO).
Fix's HY Neuro is a much more esteemed book, and isn't that much longer. It goes without saying that FA has everything you need to do well on the step, so use that primarily, supplement with qbanks, and use review books where further explanations or connections are needed.