You implemented good idea here. I must say that it is not the most original one but it has the emotional reverberations. I like her pose. She looks careless at first glance but later the tension becomes notable. She is like a guardian watching over the city. You did a very good job with the girl's texture. She looks like a natural part of the scene. Probably her hair needs a bit enlightening at the edges because it is the closest part to the light source.
I think you chose the right color scheme. Smoky greys give the picture a bit dreamy look and lead us in the fictional world of monsters and superheros.
Overall I get the feeling of an intriguing, mysterious and charming story. It's like I'm watching a movie, not a picture.