This widely discussed first book by Derek Landy appears to belong to the "love it or hate it" category. It's not great literature, but it is very enjoyable. Though I'm uncertain whether it deserves the huge advance or the massive hype long before publication.
Skulduggery Pleasant is not so much fantasy - despite having a skeleton as its main character and bits of magic here and there - as a good old-fashioned crime story with plenty of action. The protagonist is a detective, who also happens to be dead. At the funeral of a friend he meets the friend's twelve-year-old niece Stephanie, who subsequently becomes Skulduggery's sidekick. It is the death of Stephanie's uncle that sets off a series of events that has them chasing the evil enemy back and forth across Dublin.
The story has relatively few characters, so has none of the problems of keeping track of endless new strange names that you sometimes get in fantasy. What particularly stands out is that the main characters are kind and friendly in the nicest way. The baddies are satisfyingly bad.
Derek Landy does a nice line in sarcasm and irony, with plenty of humorous dialogue. The reader shouldn't take any of this seriously; it is sheer entertainment and ought to appeal to many young readers.