The first thing I thought after having "met" Wicked's version of the Wizard was that he was more villainous than I ever remembered him being in the movie.

The Wizard in The Wizard of Oz incited fear in his people not because he was evil, but because he was afraid.

He didn't know how to run a kingdom on respect and dignity of the individual, so he turned to tyranny and intimidation to ensure things did. However, in Wicked, the Wizard is more than apathetic to Animal suffering

This is another reason I'd like to read the original book the Wizard of Oz and haven't gotten around to it yet. I am curious to see what Gregory Maguire took from the movie versus the original book. I know the movie changed a lot from the original version such as the ruby slippers which I read were silver in the orignal novel.

In the movie he used his theatrics to frighten and intimidate but the movie still kind of made the Wizard out to be a generally nice old man who went about things in the wrong way, but ultimately wanted to help. The book made him more cunning and evil than in the movie and his motives were selfish.