More like 3.5 stars than four, really, but this was a better book than the first two, so rounding up to four. Also, I read this in one evening, which doesn't happen very often these days (okay, it's a reasonably short book, but even so), so that counts for something, too.
Daine's getting more and more super-powered was a little annoying, but at least there were good reasons for it, but I do wish the other characters existed for more than props for Daine to interact with when needed. It's been three books now and I still don't really feel I know any of them (including Daine, for that matter, but ... well, she only seems to have a couple of thoughts in her head, i.e. obsessing about animals and the destruction of her home, so perhaps that's all there is to know) - even Numair, and I assume we should be caring for him at least a bit by this point. He's just... there, though, for Daine to react to. :-/
On the other hand, once again the pacing was good, and there was a lot going on plot-wise, so while I can't say I am impressed by the handling of characters, at least Pierce can write a good enough tale.