One of the problems with writing about ISIS is how quickly things change. This book certainly doesn't fall into the “hastily cobbled together to cash in” category: but reading about the Charlie Hebdo killings in a book that was released only a few weeks afterwards is still rather odd. And the ability to do so belies the main problem I had with the book — it's mostly just plain factual reporting. I'm very far from expert in this area, so there was a lot of new information to me, but I was constantly struggling to piece it all together into anything coherent.

In that regard, I found The Atlantic's What ISIS Really Wants feature much better. I came away from that thinking I understood the issue better, rather than simply having more facts. Yes, it oversimplifies at times, and gets a few things wrong (Think Progress, for example, have an interesting response), but I'd recommend reading that article first, and then following it with a book like this only if you want a deeper factual background.