I used it but found the washer fluid washes it off too quickly so I started using the polish I use on the rest of my xB which is also recommended for glass. RejeX is a polymer coating which seems to last longer than rainx and makes water run right off as well as bugs an sap not stick. Doesn't desolve with the alcohol in the washer fluid and is so slippery that you can wipe the dirt and pollen off the windshield with dry wiper blades. I also applied it to the outside and inside of the power window glass and they go up and down easier and stay cleaner. It also keeps the body slicker for better FE! Dirt just rinses off and bug wipe off when wet or rinse off with a blast of water.
The only negative to Rain-X type products that I can think of, is that when driving at night, the combined reflection from the drops on the windshield can "flash-blind" you when the light source hits a certain angle when driving under overhead street lights. Not a problem if you are prepared for it, but the repetitive flashing can be annoying when driving under an endless string of overhead lights on lighted expressways.
Also in the winter it makes the nightly dew accumulations more likely to supercool, so that it will suddenly flash-freeze across your windshield when you slam your door or turn your wipers on to clear your windshield. Its kinda freaky to see it happen, your entire windshield turning from water to ice in less than a second. And then you have to get back out of your car and start scraping ice when you thought all you had to do was turn on your wpiers and drive off.
Also in the winter it makes the nightly dew accumulations more likely to supercool, so that it will suddenly flash-freeze across your windshield when you slam your door or turn your wipers on to clear your windshield.
Too cool! I would love to see that some time. #1 son has seen the supercooled Corona trick on YouTube and wants to try it at home...