I started rereading this to prepare for a game (that I didn't end up running). I remember loving this book when it came out, but now I found that though it was broadly good, so many little things about it grated on me that in the end reading it wasn't entirely pleasant. I'll start with the good: all three groups described have character. They're a mix of good and bad, something that in many ways M20 has forgotten about the Batini, Taftani and Djinni, and their intersections are all fraught, perfect for stimulating plot in a game.
The bad, unfortunately, starts with a common problem with Mage books: the IC/OOC divide is often hard to detect, so things that only make sense to be coming from an in-character perspective are written in an omniscient narrator voice, and vice versa. As an example, after a long section describing how the Batini use the Mind sphere to "guide" recruits towards the correct conclusions, there's a sidebar stating that this isn't brainwashing because it's not exactly like what the NWO does. Instead, it's like the brainwashing that a real-world cult does. The history in the book is laughably inaccurate (to the point of claiming Solomon built a city to act as a trading hub between the Roman and Persian empires), the Batini section on Kabbalah is all sorts of terrible (and the section on Kabbalistic books is...something else, entirely ascribing to mages books that exist and are sacred in the real world), and then a multitude of minor gripes.
Overall, the book is good, and if you want to go into depth on the Ahl-i-Batin and Taftani, it's a must have, and the Djinni as described here are more interesting than their portrayal in Gods and Monsters.