Another in the growing genre of fantasy parodies, this book is loosely anchored in Hamlet but covers everything from the Oracle of Delphi to bland American beer and Starbucks coffee shops. It is full of "meta-humor" -- jokes about itself and the genre it is part of. Most of them work, but none of them are as shockingly funny as those in a Chris Moore or Douglas Adams book.
As a typical example, consider the scene where Charlie meets the ghost of his murdered father (the former king). Charlie dislikes his dad and is glad to tell him that he is working with his father's murderers. He also warns him that he is not interested in listening to the ghost's story, because he knows the ghost will vanish at dawn just before he reveals some crucial information. And, of course, several pages later, that is exactly what happens, just after the ghost has finally convinced Charlie that he should pay attention to the problem he is worried about.
The humor and the characterization are well done, but unfortunately the plot is a little bit underbaked. It is slow and overly complicated (which could also be said of the plot of Hamlet). The jokes and the plot keep fighting with each other over which element gets to take center stage (unlike, for instance, Patricia Wrede's Enchanted Forest books, where they are much more symbiotic and complementary).
The book is written for adults and older teens -- younger readers (and those unfamiliar with Hamlet) will miss many of the jokes.