I love the mannequin. It's so easy to pose compared to ZBrush's offerings. However, there a few things I would change about it.
I would adjust the index finger rotation (seems off from the rest of the fingers) on both hands, give ball joints to the joints, which would also help with the filling in and sculpting later on and I would add a cross section to the palm area, both vertically and horizontally, so that the palm could be "cupped." I would also make the Midsection a child of the Pelvis. I would also add one cross section in the neck for bends.
I realize the mannequin is for rough poses, but I think this would help. I generated this magic caster pose that I think these changes would have helped with.