Very cute! Like the pose and the catchlights in the eyes, but the eyes don't seem so sharp. Also, it appears there's too much of a light differential between the left and right sides of the boy's face and the shadows are deep under his chin. This takes a little away from the typical light/happiness of kids, for me anyway. You captured the skin on the girl's face excellently - it appears silky smooth!
Awesome, warm, gorgeous. Those are my words here. Cropping off the edges of all the body parts brings me right in to what I need to be looking at, I like this.