First of you don't paint aluminum. Second it is a good product but won't stand up to abuse. IF you don't protect your phone's finish with a case or sticker protection of some kind don't complain when the *anodized finish starts to wear off. Imagine you rubbed the same spot on your cars finish (even though it is painted) over and over and over and over again (much like you do with your phone when going in and out of pocket, setting it on a surface ect ect) how long do you think that spot would stay pristine? Yep, same with a phone's surface.
Apples and oranges. Industrial strength anodizing is made to last and goes deeper into the aluminum than is possible on the iPhone. Continually rub that part in the same area over and over again and it WILL wear off.