The mysterious group of characters introduced at the end of book 2 dominate the first half of book 3. Interesting, but at first I was a bit confused. These characters seemed to be part of a flashback in book 2, and I assumed the flashback was continuing in book 3. It wasn't until around the middle of the book that I realized it was not a flashback, but events happening elsewhere in Midgard. (Incidentally, the reason I thought it was a flashback is because I thought the little girl was a younger version of Iris Irene.)
Besides my initial confusion, I enjoyed it. It seemed much more "serious" than the previous two, with a lot less chibi art. The one thing I did not like was the fight sequence at the beginning... it went on for the entire first half of the book with very little dialog. I wouldn't have minded, except many of the scenes were confusing and hard to follow (even after studying them intently for several minutes). But, the second half of the book was packed with great story-telling, so it wasn't a total loss.
And, of course, the artwork is fantastic!