Poor little kid doesn't look happy to be out and about "modeling." Your photo is okay, but reminds me of a vacation snapshot. I wonder how this would have looked if taken from a lower angle or maybe closer to the child and using the waterfall as a background.
I see your thoughts in the composition of your picture. I'm not too fond of the big areas to the top left and top middle. They are basically empty and do not add details or have any othe function. May be alower angle (height of the child's eyes) and framing the picture really around the kid and waterfall only could make it stronger.
I am struggling to find something that keeps me looking at the photo. The child steals the waterfalls limelight, mainly because of the bright yellow jacket.