It started off ok. A little same-old-same-old - girl in difficult world must help family by being brave but something bad happens and there is a boy who is handsome etc etc. Well written enough that the cliché was easy to get past. Penryn is actually pretty cool. She is legitimately kickass, meaing that it's not because she's a prodigy or a genius or anything, but rather a difficult home life and the circumstances around this led her to have taken martial arts classes for the past ten or so years. So yes, she is genuinely tough which makes a nice change.
The romance made a little more sense than other YA novels usually make it (though the age gap is a little creepy once you work out that Raffe is probably around, oh, 3000 years old or so) and the characters seem to have fairly realistic reactions to everything. Not sensible, of course, but then sensible would not be realistic in a newly post-apocalyptic world.
There was a little too much setting up for the sequel, and purposefully leaving things out until the sequel. This would have been ok if the last third or so of the book didn't get so boring and so weird. Don't get me wrong - I love weird plots and writing (Ape and Essence is one of my favourite books of all time. If you read it you'll really see what weird is, in a good way!). But this weird is thrown in there with angels casually having club nights in the middle of destroyed San Francisco and just didn't seem to work. I know something's wrong when I would be happier for the cannibal creatures to be deranged humans than the surgically altered razor teethed zombie children made by angels from hell alongside scorpion demon/angel things. I think the only way I can really explain my disappointment of the "strange" stuff is that it felt like a cop-out. Throwing in more weird hybrid creatures and evil villains and such does not makes a book better. If this was a standalone book and this had been the case I would be more inclined towards two stars but the sequel may redeem/make sense of the last part, and the rest of the book was pretty enjoyable.