My god, what a clusterfuck. I am so unbelievably disappointed in the direction this series has gone, and particularly how it ended. I have no problem with this as a children's series, I am an adult and I love my YA/children's stories, but I'll be damned if my childhood self could keep track of half the shit that's been going on and adding to the massive pile of poop that's been gathering since the second book. 
 The increasing number of characters, the many many places/times/dimensions to which they have been split, the many points of view the reader is forced to assume. There's no way a child would enjoy the latter books in this series. This last one has my head spinning, and I had to force myself to read through it simply because I didn't want to have myself suffer through the previous confusing books in vain.