The hair can be a little difficult to build because it some some thin parts, but if you take your time and don't get frustrated (it's only paper ;o) people should manage (I see examples of people building far more complex paper models than this one every day!)
All that's left now are the arms and hands. The arms won't be much of a problem, and the biggest problem I foresee with the hands is the small size of the fingers. But because they're basically just cylinders, you can practically make them just by rolling them around a toothpick.
It's a "trick" I used for making Super Smash Bros. Melee Link, and it made building the fingers very easy.