The art looks great! My only suggestion would be to make the important gameplay elements brighter and more vibrant (higher value and saturation) so they're easier to make out and the background darker and more muted. Admittedly, this is easier to do in games that are more colorful, and you don't want to lose the nice gray urban look you have now.
If you're adding more juice, it would be cool if there were something to make the jump/doublejump state clear just by looking, so that hopefully that information could be removed from the UI altogether.