At least it reminds abusers about one of the potential dangers they face.
Here in Costa Rica they had a PSA where they showed a flower and then somebody's boot crushing it, and the slogan was something akin to "hitting a woman is like destroying a beautiful flower"; and I don't know, it just seems to me that guys who beat women unconscious are not the type of people who take the time to enjoy the simple beauty of flowers.
I think the Canadian ads have a better handle on it.
http://poetv.com/video.php?vid=4279
I like Canadian PSAs because they're not inherently legal-positivist; you shouldn't hit your wife because it is an ugly and loathsome behavior, not because it is going to land you in jail. You shouldn't drive while high not because you'll be punished if you're caught, but because you are just way too damn high to be driving. I find it insulting to be threatened rather than reasoned with, especially since the consequences of breaking a law are already a basic part of living in civilization and advertising them just seems oppressive.