I love the use of color in this portrait. The splash of blue between the boys is great next to their blonde hair-- it really draws the eye to the center of the artwork.
The piece is well-balanced between the axe at the top and the boy's hands at the bottom. I especially love how alive this style is, the lines are gesture-like and suggest movement. action, as well as set a mood for the portrait. The kids look like comic book heroes and I bet they love it.
The detail in the axe shows technical skill/attention to detail, the style makes a great impact on the audience, and I would say it is an original portrait.