Please allow me to explain how to fuck up an easy novel. First, take an established universe with loved environments and characters with an ambiguous history. Within this universe, select a character that the reader was never asked to identify with and was never explained their motives. A character where you can leverage their mysterious past to turn the reader's opinion of this character on its ear. Once you have these two elements, throw them on the ground at your feet, unzip your fly and take a big steamy piss on them and then go and write some boring ass shit about the most uninteresting person in existence.
Here it is: The Wicked Witch of the West is a fucking nerd. That's it. End of story. She's born and her parents are embarrassed that she's green. Then she goes to college and people are more critical of her clothes and attitude than they are about the fact that she has green fucking skin. She acts above it all yet hasn't a single interesting thought or opinion (besides the inhumanity to Animals, which I will get to later) shared with the reader. Then in her mid-twenties she joins a terrorist faction bent on deposing the Wizard. This is where it seemed to get interesting, but right before it does it fast-forwards a decade and she's in her thirties and she's fucking boring again.
Without going into too much detail, at this point she goes on this contrived journey
to apologize to someone she wronged in her revolutionary phase, but ends up owning their castle because they get kidnapped. I could explain this better, but I hated this part of the book so much that just thinking about it again will probably make my nose bleed.
Ok, she has a castle (with flying monkeys at this point, although to the author's credit, he does explain this one), then the horrible tornado happens and drops a house on her sister, who incidentally ruled Munchkinland. But get this, she doesn't even like her sister. Whoa, what a twist. I can just hear people in book club meetings now, "Man, the movie totally made you think she was mad about Dorothy killing her sister."
So, she gets involved in trying to get her sister's shoes back from Dorothy because the Munchkins viewed the shoes as an icon of her rule and the Witch didn't want the Wizard to have them and thusly be able to control Munchkinland (good plot point). Then, after the Wizard sends Dorothy off to kill the Witch without taking the shoes, she even admits she's confused as to why she's still after Dorothy (really bad plot point). I'm not even going to touch on how much everything that happens in this time frame contradicts the movie. I suppose it's too hard to actually show interesting but overlooked facets of a old and much loved story (zing!).
On the upside, there was an interesting sub-story that ran throughout the book (kinda). Apparently in Oz, there are animals (like the ones we know), and there are Animals, the kind that can walk and talk, like the cowardly lion from the movie. In the book the Wizard had begun a sort of retraction of Animal's rights and tried to relegate them to the fields as beast of burden, like their kin, the (lowercase) animals. This was the reason the Witch joined the terrorist force against the Wizard. Also, the reason this sub-story couldn't save my opinion of this book is because it seemed to last about as long as this paragraph.
In summation, this book was written for goth kids who are enamored with the thought that although they are ostracized because they lack any social skills, they are so much deeper and their misplaced convictions are so much stronger than anyone around them.