Very nice stuff, the forms are pretty good, however there are a few inconsistencies in the directions of the shading and there could be a tad more contrast in some area's, such as the brows/eyes. Other than that its nice, got a very evil smirking feeling to it
The eyes make it look like one of Elder Scroll: Oblivion's characters, the lips, chin and eyes are very feminine, while the jaw bones (I think that is what you call 'em) are very manly. Nose is compared to the rest of the face way too large. Overall apart from the horns, it doesn't look that much like a Devil. It's a good drawing, but certainly nothing Devilish.