What the heck is up with Wicked??

So, I'd eventually like to see the show, Wicked. I figured a good "taste" of what the show would be like would be to read the book by Gregory Maguire. All I have to say is OH! MY! GOD! I mean, this is supposed to be Oz, people. A happy place with munchkins and whatnot. I mean, I figured that it would be an even happier place without the mean old green witch. Not so. I'm forcing myself to read this in between book club books, but man, I never dreamed of an Oz like this!