I love my polarization sunglasses. The cheap ones that I used to wear didn't do much to reduce the glare from the sun, but these polarized ones work wonders.
I have to drive home facing the sun as it is setting, so the glare can get pretty intense. With my sunglasses, I can focus on the road without having to squint to filter out the intense light.
Also, I don't see the glare on my windshield. If I take the sunglasses off, this glare is blinding, and there is no way I could safely drive without them.