this is really awesome and represents Goethes masterpiece in a perfect way. you did a really awesome job with all the details, the expressions and the whole composition. I really love that picture. Faust is a really great book, and it's great that you drew a picture of him and Mephisto (I'm not sure about the spelling, I don't know how it was translated but in german it's "Mephisto" with ph)
btw Mephisto looks somehow sexy xD