The tone is almost good, but if you wanted to keep their nationality, you need to make their skin darker. Faces are so bright you even lost shadows and highlights, which makes it flat.
Second thing watch - your line when doing wrinkles and muscles on face, you push a bit too hard. It almost looks like they have mustaches and you kind of lost their expressions. The boy looks evil and the girl just strange.
But the rest is awesome! The folds on clothes, their pose, great stuff. Just please do something with their faces.