The arm's my favourite part (as it should be), especially the shell like parts surrounding the cables, and the joints at the shoulder and the elbow. The eye, nose and lips are also at a high standard.
My problems tend to arise with the angle clash between arm and her body - she's positioned at a 3/4 view, whilst the joints in the arm would suggest we're looking at a side elevation of the arm. There's no twist in the shoulder or the upper arm to accomodate this change in angle. The other thing is the arm hides up her ribcage, which looks a bit distorted. The closest boob is hiding under the arm pit, and the base of the rear boob looks like it lines up with the lowest rib.
Ignore the length of the criticism, however, since it's a great starting entry.