I actually think the dog looks like its just launched, and we have no idea whether its athletic enough to make it, or if the little boy can even pull that big ol thang up. i like it, and i like the colours.
i would make the boy pop more, heres an edit wot i did
more contrast, and saturation places. i tried to add more contrast between the boys own colours, and more contrast between the boy and the background. you could add more for sure. I also got rid of the outlines on the boy, they didnt make sense to me.
apart from that you also have some banding on the rim lights (i think thats what agent00x was getting at)
<edit> oh and i got rid of some of the colours in the boy, the shoes, backpack and furthest arm are now the same colour
great pic!