It seems to work okay with my glasses on, although I think it works better with my glasses off. Fortunately for me, I can still see pretty well without the glasses on.
I'd say it probably depends on the glasses. I imagine glasses with thick frames ( especially that are a color that is high contrast to one's skin tone) or thick corrective lenses would have more of an impact than thin frames with a milder prescription.
Also, you want to reduce any reflections on the lenses. Although the face tracking works better when you have a well-lit face, reflections from a light source can affect the tracking.
You can also turn down the strength of the eye gaze based on your own eyes, and enable the eye gaze to be controlled by the mouse (or combine them). Some people prefer this more manual control.