I like that is not extremely real -talking about the shading and the reflects of the eyes- but I just added it as one of my favourites cuz it kinda reminded me the movie A scanner darkly... she's just missing the roaches all over her body!
I'm usually really sick and tired of this image, it appears everywhere and it's seriously overused...
But you did a really, really nice rendition! I like the tousled hair, it accentuates the expression superbly -- like she's just been handled roughly or something along those lines, as opposed to just... looking like a girl with duct tape over her mouth. Her expression looks so stunned, its perfect.
The lines is so beautifully clean.... I have to say I really admire it. Shading is excellent too, all the contours of her face are spot on.