I'm probably being too kind with my rating. It's MAYBE worth getting from a library (if you can find one that has it) and SKIMMING it if you REALLY REALLY love Wicked (which I do), this is the most horrible book I've read since middle school.
Avoid ALL books by Paul R. Laird, in my opinion. This book read like a really bad 7th grade book report. He started by summarizing, he quoted the GOOD books about Wicked (David Cote's Wicked: The Grimmerie, a Behind-the-Scenes Look at the Hit Broadway Musical & Carol de Giere's Defying Gravity: The Creative Career of Stephen Schwartz from Godspell to Wicked, which devotes a large section to Wicked), which I already own and read.
He even started one chapter by saying "In the last chapter I..." SERIOUSLY? I'd READ the last chapter, jerk. I was seriously offended by this book. No intelligent human being should consider it.
He would talk about some changes made in various versions of the songs, but NOT actually show the changes, just say that changes had been made. Really??? Enjoy the other Wicked books. Stay far away from this horribly written book.
Parts of it are worth skimming, since he does include portions of various versions of the script, but I find it very difficult to believe that he actually spoke with Schwartz, as he claims. If he did, why did he write his own book like a terrible book report with more quotes than actual ideas? It was insulting.