I am curious as to how you modeled this arm. Was it fully polygon modeling. Really it looks okay, and I would like to see it with a subsurf modifier.
Honestly for organic modeling I would say that the best way to go would be to use multires, and up it to the maximum, and model out your body. Then set the level lower to get polys between 2000-5000. Next you up the multires to the max again, and start to model the details. Then bake a normal map out of that, apply it to the lower mesh, and it looks perfect.
I used to think the opposite way was the best, but after spending some time around the Blender community, I would say hires->lowres->hires is your best bet. Just make sure you don't add any details in your first hires mesh!
Yeah, as JP said, the fingers are very out of propotion. And you should vary the lengths of the fingers, as they are on your hand. (I hope. ) But otherwise with subsurf 4 on it looks very smooth, and very good. This looks as if it could turn out to be a perfect low-poly person model, and hi-poly model if a normal map was baked for it.
I'll scale the hand down to the right size. I'm still trying to figure out the contours of the palm and fingers. They still look pretty hard to get right on low-poly, though.
I'm still wondering about the hires-lores-hires transmutation thingy. I thought starting low-poly is OK since I have the vertices sitting at the right position, then adding the hires layer inside the lowpoly will provide the baked texture. Can we discuss this a little further, I'd like to more about this stuff.