I liked the character resolution for Artemis and some of the reveals about history that the series kept for this last book.
I might comparet to the Young Wizard series by Diane Duane or Terry Pratchets Discworld series. The humor is cleaner though. Both sereis deal with characters dealing with the supernatural with a mizture of humor and wonder.
Artemis was my favorite of coarse.
While this was a great book in the series it was less than I expected for the final book of the series. I thought there would be more of a final big revelation or change for the final book. But if you liked the series go and buy this book.