The background is really neat. I like how it's dark, grungy and falling apart, gives a good atmosphere to the wallpaper. I think the one thing that ruins this wallpaper is the scan not being good quality in some parts. I see you tried to really touch it up, but being a highly detailed manga scan, it's very difficult to touch those up.
However, the nice brush of streaks, that look like webs, or scratches, give it even more depth. The shiny star or whatever you'd call it seems unnecessary, I don't know why it's there. It's not part of grunge walls, it seems to be out of place. It's a good use of brushes, I congratulate you on this work, keep at it, and you'll become even better within time.
