This book was a disappointment after the first two in the series, both of which were vivid and riveting. Fortunately, I had been forewarned that this one was a bit lackluster, so I didn't go into it with expectations that were too high.
Mostly, it felt like a sequel that didn't really need to be written. I think the author (or publisher) felt compelled to tie the first two books together, but both of them are strong standalones and tying them together in this third volume felt forced. Plus, a lot of what happens in here is not very different from what happened in the earlier books -- the struggle to find enough food, the windfalls and disappointments, the highs and lows of living through an apocalypse, you know, that sort of thing.
And even though it's shorter than the other books in the series (I think), it has a lot more characters, so there was quite a bit to keep track of in the second half. The book started to feel "crowded" since several of the characters were not developed all that well. Also, I noticed some really weird gender things in this book that either were not present in the other two books or that just didn't strike me in the same way. But I think that Pfeffer might have some internalized sexism going on ... Miranda's mother was always very insistent that Miranda stay home while the boys were able to strike out and explore/adventure/etc., and Alex seemed to think that for some reason he got to decide what his sister's fate would be even though she was old enough to have some say in the matter. (Also, I think the decision the author made regarding Julia's storyline was absolutely atrocious). I liked Alex less in this book than in the book that is actually about him -- in this volume he came across as controlling and almost stereotypically pious.
For whatever reason there is yet one more book in this series, which I may or may not read. The first two books are great, but as far as I'm concerned you wouldn't be missing too much if you just stopped there.