That is the quality I think of when I look at this image. This lady is about 60 and has worked by the sweat of her brow most of her life.
Just a quick comment, she just doesn't smile much.
My technique for shooting at slow shutter speeds is to set the camera to manual, select a shutter speed (anywhere from 1/10 to 1/30) and then shoot at least three or four in sequence mode. Usually the middle ones are pretty decent. I like to shoot with available light and this works well for me.
cropped
adjust levels
adjust contrast
adjust shadows and highlights
adjust contrast
resize
a little dodge and burn
gradient map at 90%
remove a couple of spots
USM
double pass of noise reduction
The angle, the light, and the tones truly deliver the character in the face. Not everyone has to smile, and I think we are often mistaken in our reading of an unsmiling face. I see a woman who knows her own thoughts.
Wow, that's a pretty sharp image for 1600 and 1/25, well done. Like the processing. I am wondering what she is looking at, something appears not to be pleasing her.