I like the development of a 'fleshy' three-dimensionality to this image. The contrast between the flat strictly 2-d aspects and the shaded and rounded face leave a lot of room for metaphoric interpretation by the viewer.
You have many very beautiful watercolors that are vibrantly colored mixtures of simple line and more complex detail areas. This image stands out though as the more complex areas are made more 3-D by your use of shading. The white of the underlying paper becomes true highlight, rather than just empty canvas. This is true of your piece "portrait practice on moleskin" as well, where such depth is created as to give the empty white areas the appearence of paint on skin, rather than empty space.
I wish the contrast were pushed slightly further, with somewhat deeper shadow areas. But the strands of hair across her face are wonderful for accenting the three-dimensionality you are creating. They are well crafted as well, with a very real whispy feeling, yet long and heavy, adding to the overall mood of the work.
The eyes are perfection. The soft quality to the lashes and the closed position creates a feeling of quiet, you can almost hear the thought-heavy silence. The image abounds with room for the viewer to engage. The gesture, the contrast, the quiet, the color, all speak volumes; creating a mystery any viewer could fill with their own experiences or could spark greater imagination.
Overall a well crafted, complex image radiating emotion.