Interesting photo

There is no question in my mind that it is simply a person walking past, however.
The trail of her movement is evident in the clothes (along the print), the back of her head, at her arms, etc. Also, as you pointed out, her irises reflected light, which is another sign of a "solid" presence.
Ghosts, spirits, etc. are "energies" - they aren't solid matter. Ghost hunters also use frequency meters to detect spirits through their energies. The lady was walking past and she is "solid". Anything moving in front of the camera lens - especially a digital camera lens - with a slow shutter speed will look blurry.
Try swinging out hands as you take a picture of someone, or moving your hands across the lens as you click the shutter. It will look ghostly as well.
For your viewing pleasure (freshly taken! you can even see this post in the background):
Against a blank background
Pretty ghostly, huh?
Also, ghosts or spirits that choose to show themselves to people usually have a message they want to get across - that is why they communicate. In this sense, the lady is neither directly looking at the persons on the image or (most commonly) at the photographer. Her expression is also rather distracted, and not unlike any other person trying to pass by to get to where they want to go.
It is all open to discussion, of course... but that's my basic opinion of it.