The Serpent's Shadow

I recently finished a book, The Serpent's Shadow.  It is the third and final book in the Kane Chronicles.  The two main protagonist are Sadie and Carter Kane.  The book is written in first person and alternates between Sadie and Carter as narrators.  In the first book they discover they are descended from the Egyptian Pharos and have the ability to use magic.  They discover that many gods, goddesses, and other mythical beings actually exist.  The series is very similar to Percy Jackson and the Olympians; it uses Egyptian mythology instead of Greek mythology.  Both series are written by the same author, Rick Riordan.  I'm not the bigest fan of the book.  The characters aren't developed and are very one dimensional.  They lack complexity.  In the book protagonists are always good and the antagonists are always evil, while the line between good and evil should be thinner.  The book lacked larger themes and was, like the characters, one dimensional and didn't represent any more universal issues.  The writing was not vivid and was unable to clearly describe scenery or characters.  I wish the writing would be more concise.  I am being a little overly critical; Rick Riordan cannot compare to Ernest Hemingway.  The Serpent's Shadow is a great quick read for anybody who loves action, adventure books and has not out grown Rick Riordan.