I think what rubbed me the wrong way about Fallout was the brutal reality of it. Hopkins breaks the fourth wall with this one, and it serves as a stark reminder that there's not always happy endings. Fictional and real Kristina didn't even stay around for her children, get better for the daughter she hoped for at the end of Glass. I understand other reviewers frustrated by the way all of her children turned out and acted, and I initially was, too, especially with Hunter. But in one of his chapters it was said best: genetically predisposed. Actions have consequences even two decades later and even for people who didn't deserve to be affected, unfortunately. I had to think long and hard about what to rate this book, hesitating because as real as it was, it didn't capture the same feeling that Kristina's point of view did. And to be frank, at certain points it felt much like a weird form of child pornography - Hopkins, piece of advice: we know teenagers have sex. You don't have to write about it in such vivid detail every other page, and you also kind of ended up making it feel like sex was a bigger "monster" than meth - pregnancy, rape, cheating. 
But anyways, I digress. I couldn't give this the same solid 5 stars as Crank and Glass, but it was still thought provoking and a completion to the journey.