I thought the writing was beautiful and compelling. I actually think we learned just enough about the end of the world as we needed to; I liked that what happened was never clearly laid out. It didn't have to be; it was enough that it had happened. 
 The only thing that struck me as off was the ending, which felt a little too contrived and neat. Although I also felt like maybe it was a metaphor I was missing? 
 (view spoiler)[ 
 That man-- a good man, with a nice family, the only one we meet-- appears right when the boy needs him, so he doesn't have to be alone? Maybe it's supposed to be evidence of God, or the fire they carry. It read like deus ex machina to me anyway, and that wasn't what I wanted after all that hard slog and fight. Then again, I spent a lot of the book wishing they'd hurry and up die to get it over with, and I'm the sort of person who has a pact with my loved ones to all die in the event of zombie apocalypse rather than try and survive. I guess what I'm saying is, if there was a supposed to be an underlying theme that life was worth it in spite of everything, I didn't really feel it. (hide spoiler)]