The knee-jerk "Needs fill" in response to not being able to see her eyes clearly
It's not that.
It's that the model has ALL of the detail in this photo. A really intricate knitted top, the necklace, face, hair, everything I might care about in terms of interesting stuff in a photo (since otherwise it is very standard)
But ALL of that detail is completely flatly lit and dark, so my eye doesn't go to any of it. My eyes spend their entire time in the featureless, boring curtains, until I get tired of curtains (which is very quickly), then I move on from the photo entirely and do something else.
Like I said, if his goal is to show off the curtains, then it's great. Otherwise, I can't really think of any goal the photographer might have had that this photo would accomplish it, in terms of "I think I see what you are trying to do." I think what he is trying to do is to take a standard portrait picture of a girl with a nondistracting background and plenty of detail in the girl to keep us interested.
That's what it looks like he is trying to do. And that's the opposite of what the lighting achieves.
By contrast, the photo in this thread here has super dark parts of the model, and you can't see her eyes at all, but I think it is extremely successful, and said so (I didn't suggest fill light there):
http://www.thephotoforum.com/forum/black-white-gallery/338379-black-n-white-story.html
The difference is that the B&W photo clearly seems to be trying to go for form and pose study and mystery, and the lack of fill accomplishes those goals (the outline and lit portions are enough to see pose and form). Whereas this photo does not have any air of mystery at all really, nor any particularly unique pose. Just a girl sitting in a window. The interesting part of it is therefore not the overall blunt shapes (which you can see, but aren't terribly interesting), but instead the details are what's interesting here. And those are lost in poor fill.
So yeah, I considered what it looked like he was trying to do. And that's what he does
not seem to be doing in that photo.