What makes this excellent is all the little details. Scabbers, Crookshanks, the expressions on the faces (love the cloud over Snape). I would like permission to use this as an illustration in the Young Adult Literature programming track at Dragon*Con this year. PM me if this is OK.
I really love caricatures(spent an exciting but grueling Christmas season doing 'em in a mall), and you really captured them,especially Harry and Snape. Great job!