Interesting
I like how you used a mixture of blue and purple, and even a bit of green, to darken some areas rather than the boring black and grey; it really suits the theme. There's good use of lighting - especially in the eyes and lips and I can tell you have an eye for detail.
I'm trying to figure out what tools you used, am I right in thinking there's both oil pastels and colouring pencils?
Overall it's a really good image and there's nothing really I can find wrong with it.
Some positive criticism, however - unless it's a style or something, I think you need to keep the detail consistent throughout the image. I can see you put a lot of work into the face and some into the hair and chest, but the arm in the background looks a little awkward and rushed. If I finish the picture in my head, the angle on the forearm makes it look inhumanely long.
But that's only because I'm really critical about detail, anyone else would call it perfect.