It should also be noted that the 1939 movie was not totally true to Baum's book.  There are many parts in the original book that are much darker than the movie.  For example, the tin woods man became the tin woodsman because he was cursed and ended up chopping off his own appendages.  This is actually mentioned in Wicked and it's Nessarose that puts the curse on him.

The Oz from the film is a happy place. There is some strife, with the witches, and some elements to be concerned about, but mostly the people are at peace and free to experience their lives. In addition, it is a rural location. Emerald City is the only urban center, and it exists not as a traditional city, but as a busy household in the middle of a field.

Maguire's Oz, however, is much more modern in a sense. There is political and religious strife, and a conflict over individual rights. There is racism and sexism, a conflict with a tyrranical leader, adultery, corruption, and cities with public transportation, bars, and bordellos. The characters have much more depth, and constrast their movie counterparts. Glinda is shallow and vain. Dorothy et al are portrayed as needy, grasping, and of little importance. Elphaba (the wicked witch) is a neglected and tormented child who grows into a bitter and disillusioned rebel and outcast. Unlike the villianous character of the movie, the book portrays her as a tragic hero, trying hard to improve the world around her, but letting her resentment and fear cause her downfall.