Meh. Kids aren't off-limits in a public space. Selling or licensing their likeness? Now that's off-limits without a release.
I don't like how dark the child is against the fountain. His hair has been clipped to pure black. And the fountain is a neutral grey. This makes me suspect that you may have used an automatic mode (such as Av, Tv, or P) and didn't compensate for Canon's evaluative metering system. Unlike Nikon's matrix metering, which uses colour to more accurately adjust exposure automatically to render scenes correctly (such as making whites white, and blacks black, or not over- or underexposing colour channels), Canon's evaluative metering system only uses grey tones (with the sole exception of the new 7D which uses colour in its metering system). To account for this, when shooting a scene that is predominantly white like this, you should dial in an exposure that is a third or two of a stop (and in some cases a full stop or more) higher than what the meter dictates when in evaluative mode. This can be done in manual by setting exposure so that the meter reports overexposure, or by dialing-in an EV comp in any of the automatic modes of a third of a stop or so. This would have brightened the fountain so that it was closer to white in the image (and in this case, it really wouldn't matter if you clipped the highlights of the fountain), and prevent the underexposure of your subject that occurred.
Compositionally, I think you did well. I would prefer a tighter crop, perhaps with a 5x7 aspect ratio instead of 4x6. The pose is...unfortunate. The child looks like his left hand is missing or stubby. If he was an amputee, then hey, no problem, but I get the sense that he wasn't and this is a trick of the light. When shooting candids, make use of continuous shooting in burst mode. It will give you more options later on, to choose the pose that works best for the image you are trying to create. Doing so you might have caught an image a split second later where there is more light on the child, the pose is better, and there is less contrast between the child's left shoe and the rest of his body. Our eyes are drawn from dark regions to light regions of an image (one reason why catchlights are so important in eyes), and in this circumstance, the eye is unfortunately drawn to the child's right shoe.