Although the author purports to address the issue of free will from a neuroscience point of view he goes off on many, many tangents and is oddly reticent to make any firm assertions.
He gives a good tour of the current state of what we understand about how the brain works. This is meant to set the stage for addressing the question of whether brain chemistry and wiring pre-determines out decisions or if free will really exists. However, although he asserts that he thinks free will exists he does not create any structured arguments to support his belief. Either he feels the evidence speaks for itself (in which case he has over-estimated his audience) or his hypothesis never crystallized in his mind.
As an experienced neuroscientist he has a masterful grasp of the subject (although I found his frequent, parenthetical comments of "so-and-so, who worked in a lab across campus from me" did not add anything to the story.) Not only does he understand what he is writing about, but he has thought deeply about the implications and he presents the material accurately.
I found the performance to be rather snarky and it distracted from the text.
The survey of current neuroscience makes the book worth reading, but I think he does a disservice to claim the book is about free will.
The descriptions of his patients are heart-rending, but powerful in the compassion he brings to his work. I think his scientific ideas -- that relatively mild traumas (like your mom being stressed out) during pregnancy and infancy will give you an addictive personality -- are half-baked at best and basically amount to saying that all of us are prone to addictive or compulsive behaviors. I also found his assertion that addiction did not exist before the Renaissance to be pretty odd. It was disappointing to have someone who is trying to advocate for harm reduction, a policy that is both compassionate and evidence-based, making so fast and loose with the evidence.