Her clothing has a very impressive amount of detail, depth and texture. Her daggers, too.
There are a couple of things i notice with her face. (im not aware of how shes looks in the reference) I only say these because you took it upon yourself to modify her look for the sake of a good composition. with that said.... 1) Her nose looks low and her bridge looks like it could use a little more depth (i know, shes asian, but still..) and 2) her cheeks could also use a little more definition and her jowls look SLIGHTLY swollen.
HER (one in back) left hand is a little bit hard to discern, there is a loss of definition in the palm/wrist region. (her thumb leading into her palm looks a little too blended in and cant tell where her hand starts and thumb ends)
the background is perfect. At first i didnt notice why i liked it, until i realized it was the depth of field you had. I dont see this too often (with a landscape background) in pencil drawings. i am also very impressed with the exposure of the background (and subject).
The composition with respect to the subject: the direction she's looking and what side of the paper she is on is good. she fills the whole frame, but the focal point is off-center looking in a direction that is ambiguous, sparking some imagination (or memory) in the viewer.
This is rather critical. As a piece of art i think it is very nice. I dont think that it would every be stared at as long as i did, or as closely as i did. (not because its bad, but because im giving an honest critique)
In short: this image is very impressive. there is a very slight disconnect between the level of detail in the clothing and face. The composition is average to above average.