This is one of those paintings that I have to admit for a long time I really couldn't see the big deal about. I always thought Da vinci's drawings were much better.
However lately I have started to see the painting in a different way. To the point of almost becoming obsessed with it. I have seen it at the Louvre, I never even saw the "tacky" but the eyes follow you thing. I am still wondering how that come about since you can barely move in there.
Still when you really start to look closely at the painting, well you see it in a completely different way. There is a definite subtlety there, just look at how the lips and eyes are done. Even 507 years later I wonder how many people have achieved that sort of perfection.
For a great short video, see the following, it is well worth watching.