Its white and at present its left to the elments 24/7 until my garage is ready (built!) I'll give an honest review when Ive seen the finished results and if this hydrophobic stuff does exactly what it says on the tin!
I had this done to a Jaguar XF in Black Amethyst when I got it new. Advised by the dealer it would show off the metallic colour better and be easier to clean.
I wasn't convinced by it over 3 years of ownership! I haven't had it done to the replacement car.
I had mine ceramic coated and in my mind is worth it. Not sure what brand you are using and like anything there is a difference between the good and bad ones. Will make washing easier and protect the clear coat if you cannot wash or polish it all the time. I would say that it doesn't provide the same depth of reflection and shine compared to polish, however doesn't bother me enough not to have it.