OT: 3D object - human.

[Will]

Specifically for the arms:

Tilt the thumb down a little bit, having it stick straight out looks... well, kinda painful, since I know my thumb doesn't go that far

From the front/back view, the arm needs to taper a little less. There should be a little "bump" where the palm starts after the wrist, then it would continue to taper at a higher angle toward the fingers.

The shoulders should be a little bit bigger, to go with the chest. I'm assuming you're going for a male from that, so bigger shoulders = ok

And not specifically for the arms... the chest from the front looks sort of 'barrel-ish', but from the side is non-existant. For a guy that big, the chest needs to extend about twice as far as the arms from the side view.

Hope that helps.

--edit: Actually, looking at it again... in comparison to the head, the body is huge... so, if it's possible, try scaling down the body below the neck (or scaling up the neck and head) before proceeding. I would say don't mess with the shoulders until we can see what the re-scaling does. But all the proportion stuff with the arms and chest is ok.