The windshield of my van is fun to see when it rains. Each raindrop beads up and rolls upward to the top of the window. When I bought the car, a Crystal Fusion treatment was offered for free at that time, and with the next three oil changes.
They said that it would make the view from the windshield look like High Definition and it kind of does! They also said that it offers protection against cracks if a rock flies up and hits it. That also seems to be true. I don't think we will pay to continue it after the promotion runs out, but it has been fun while it has lasted!