If you are in an area that has freak rainstorms that come down like cats and dogs, you may want this. I've used Rain-X before and totally forgot about it because I was living in an area that doesn't rain often. Now I'm in an area that pours rain and I park my vehicle outside. This helps with the visibility while driving in those rain storms and reduces that fun morning dew that develops on your windows. What I found helps me when using this is using a microfiber cloth to clean the window and dry. When dried I use a different microfiber cloth to apply the liquid to the windows and then when it's dried I use the other side of the first microfiber cloth to shine up the window. I go this route as I heard from others that this isn't good for your paint job or the plastic or something... I'd rather not make an expensive mistake and drip on the wrong stuff. I haven't used this on the interior of my car windows so I'm not sure if that would help with the interior condensation and won't try. I'll just use my microfiber cloth to wipe that down before driving. Happy shopping!