Hi Russell,
Apart from a month as a Santa photographer back when I was a teenager, these days I prefer to stick with photographing grown-ups.
That said, it doesn't matter who you are photographing, or how old they are… the rules of composition and design tend to remain the same. With that in mind there are three things that I would do to improve this photo.
First, lose the black background. Black is a really difficult background to work with, and while it has been in vogue in the past for portraiture (the 1980s spring to mind), I think it's preferable to get some texture and detail into the background.
Second, lose the wicker basket with the wheels. Everything else about this photo is nice and soft and then you have those rather hard lines breaking into the image.
Finally, I'm not a fan of the fact that you have chopped off your son’s hands. Perhaps a better option would have been to compose the image in a vertical frame, rather than horizontal.
I would make this image again, but this time put your son on a soft background, drop the monkeys in close about him and then, for good measure, try converting the image to black and white. It will make the t-shirt look less garish!
Hope this is a help!
Cheers,
Anthony
Image Doctor's edited version