Jeez, she is evil as f*ck! You really captured an evil look here. My favorite part of this drawing are the wings; they are impressing and well placed. The shading is good too but her pose seems a bit strange. The left arm is awkward but I also think it doesn't matter much.
I also have a suggestion which might improve this work; making a suiting background. At the moment it looks a bit dull, but with a BG that could be solved. But it's just my opinion and I have a thing for crowdy scenes, so maybe you should ignore this.
Anyway, nice choice of colors and once more: great evil smile!