I'll admit it: I expected to be disappointed. It would've been so easy to wrap up Ashfall's plot where it was - a sequel seemed unnecessary. I thought it would be sort of likeAshfall 2: The Sequel (Sequel to Ashfall). Thankfully, it managed to subvert my expectations. It wasn't as good as book 1, but it had a plot in its own right, and it completely justified its existence.
As with Ashfall, the book's greatest strength is its grittiness. The apocalypse is incredibly realistic and well thought-through; I always felt like this is what would really happen if there was an apocalypse. Which is what makes the whole thing so fucking scary. What stands out most to me is that Mullin isn't afraid to have his characters do bad things, things that are wrong. They're certainly better than the villains - they're not eating people or raping women - but they're shown doing things like torturing villains for information and threatening people with guns. That struck me as realistic; no one would really be spared from the apocalypse and Mullin shows this accurately.
The other thing that Mullin does really well in this volume is to give the book a very intelligent air. I really value intelligence in literature - I think that's one of the things that really attracted me to the works of Cassandra Clare. Anyway, Mullin makes it clear that he's done plenty of research, not just in the effects of a supervolcano, but also in things like medical health, how radios work, and... let's just go with anything and everything that comes out of Ben's mouth. Mullin is clearly an intelligent person, and I'm more than thankful that it comes through in the novel.
The characterization was just as strong as before. Alex still felt like a real person, and he still had a subtle but effective emotional journey throughout the novel. Darla is missing throughout a good portion of the novel, and I liked that we really get to see Alex try to get her back, and see what he is without her and how he'll survive. We also meet two new characters, Alyssa and Ben - both are just as well developed as Alex and Darla. Ben felt this way in particular, only making me more thankful for writers like Mullin. Not only is it an autistic character in a post-apocalyptic situation, but it's a well rendered one.
Alex's characterization in particular was helped by the prose. Mullin's prose is strong and effective, and Alex is given a believable and authentic voice. It's never awkward, and it more than gets the job done. The one problem I had was the way that every single fucking chapter ended with a cliffhanger, almost without exception. It almost reminded me of an MG novel - it was incredibly cheesy and annoying. But other than that, it was great.
I really can't recommend this series enough. It's rare that I give two books in a series 5 stars right in a row - this is one of those rare cases. Anyone that likes post-apocalyptic novels, or anyone just looking for a really good story should definitely give this novel a try.