I'd like to make a few suggestions if you don't mind. I think that maybe the BG colors should be a little less intense, that way the foreground character and bike would pop more. You could maybe add a little mist or fog effect to the BG to help it recede and or change the color of the line-work on those far off buildings. Also, the "pawn shop" and "open 24 hours" signs are meant to be neon. If you were to color them with that in mind and add a glow they would look really cool I think. You could do that with the lights in the BG as well.
Those are just my suggestions that maybe can make the good job you did even better, hope you don't mind.