Edit: I removed the star rating after I realized I didn't read the third book in the series. I think that might have had a lot to do with why I was confused by the plot:) However, that doesn't change the alienation I felt from the POV shift or how little the direction appeals to me.
This was a terrible thing to do to a great series. I got three quarters of the way through the book and realized that I really didn't care how it ended. Delany threw in everything but the kitchen sink to keep her series going. The first three were fun and different but with some of the major plot devices resolved the series needed a new direction. Delany gave it that by expanding one POV (Alexi) and introducing a new one (Marlaena). There's also about four new story threads put in, including a complete shift in the main characters relationship that makes it less appealing and a Hogwarts style "special" class .
For the POVs Alexi has always been an info-dump character. Marlaena is completely crazy in a tent-religion-revival kind of way. Neither of which were interesting or appealing. For the new plot lines it took the suspension of disbelief and pushed it right out the window. Delany also committed one of my personal pet peeves by making small jokes about how the characters "almost think they're in a fantasy series" or "at least we're not twilight". If you want me to take your world seriously enough to invest my time in your novel, please do the same.