The composition works for me. I wouldn't call it a great piece of art, but it is a nice snapshot that makes me smile. The mom(?)&kid in the background help IMHO to create some context and contrast to the expression of the boy in the foreground.
What I don't like is the colour balance, somehow the colours look wrong/unreal to me.
Personally I feel that the two figures behind are rather distracting since they sort of compete with the boy for the viewer's attention. Maybe cropping them out would work better.