I remember feeling thrown off after reading the last book when all of the sudden, Todd becomes the primary love interest. It made me feel like Nash's romantic story arc was a waste of time. However, perhaps because it's been a long time since I read it, I was able to enjoy this one a lot more.
Rachel Vincent remains pretty steady throughout the series. The stakes are always high, but now they've actually managed to be even higher with the new possibility of hellions taking over the human world. It's interesting to see all the characters cope with these slightly different circumstances, as well as with their own personal drama (though the drama does take a backseat to the central plot with Avari and the other hellions).
Though I don't enjoy this series so much anymore, I will be reading the final book. I'm glad it's finally ending, instead of being drawn out to a point where ending it would be putting the books out of their misery. It should be good, and fans will probably enjoy this novel for sure - it's just not one of my favorites anymore. It's definitely a decent read though.