Angst? What Angst?: People tend to underreact to a lot of things. For example, at the height of his...erm, evil, Zyn apparently has taken to stealing from the Muggles, injuring them, setting fire/blowing things up, and psychologically breaking various Muggles into being his lackeys. The author even calls him a "terrorist". The rest of the Muggles act like he's a standard rebellious teenager, shaking their heads and referring to his behavior as "naughty pranks".
Anvilicious: According to the prologue, the nuclear wars could ultimately be traced back to the abuse of eminent domain laws...which, according to the author, are inherently evil anyway.
Author's Saving Throw: In the 2001 printing run , the discussion of eminent domain and the "piercing screams for help" line are dropped, among other things. Sadly, only the prologue appears to have gotten any attention.
Designated Hero: Rah, who does absolutely nothing to try to help Zyn when he goes off on his downward spiral. Even after we're told that Zyn is forcing Muggles into submission to obey him and attacking other people, Rah doesn't do a freaking thing! Heck, Rah never does anything heroic at all!
Designated Villain: The book makes every effort to make readers believe that Zyn is a horrible person, even calling him and his followers "terrorists" at one point. The only things we actually know him do is act ridiculously nasty towards his followers and plan to move to an island.
Esoteric Happy Ending: Rah is saved and the Muggles are happy again...except that Zyn is still trapped in a cave with his starving Nevils and would not go out, still fearing the Shadow Monsters.
Padding: Lots of it, but two examples are especially bad standouts:
A chapter dedicated to ripping off the Fawlty Towers episode "Communication Problems".
A five-page poem that doesn't advance the plot, or even scan properly, and is bad enough to make a Vogon cringe.
Zyn, the "bad" brother, grows up to have reddish hair and green eyes. Rah, the "good" brother, keeps his blond-haired, blue-eyed, Aryan appearance.
What Do You Mean, It's for Kids?: Sum all the nonsense, bizarre imagery, questionable morals and bad writing, and you'll get something that's hardly readable to its target audience (children from 6 to 12).