I reworked this picture, emphasising the drabness of the background by desturating it. Leaving the absurdly optimistic billboard and the boy in colour. Again, not as sharp as I would have liked due to the conditions in which the picture was taken (moving car and small camera).
I like the effect. Two approaches to it. One, the kid might be slightly looking at the billboard, in his present pose. Or he might have his arms raised, and jump in sympathy with the emotion of the model on the billboard. Of course, either would have to posed.
It might be possible to crop a little on the top, maybe even the bottom, without it becoming too much like letterbox.