It's the last one, sadly--I'll admit it's grown on me a lot over the past two books, the pace picking up and everything coming together--and in my opinion, the best one.
The final showdown between Gwen and friends and Loki and the reapers has been a long time brewing and let me tell you that battle was edge of your seat stuff. I mean, I know they wouldn't lose because that would have been a crappy ending, but how the author wrote it. The tension of not knowing how Gwen was going to come out on top pushed it from the usual 4 star up to a 4.5/5 stars.
Seeing how all the characters we've come to know over the previous five books come together to fight the Reapers, well, I really liked this ending.