If you look at all the other OS's, they are all competing on how shiny and cool they are. They all rely on mimicking artificial substances. Metal, glass, and plastic. Competing with them is a losing battle because you'll just look like a copy of Mac or linux theme.

What I would like to see is something based on natural and organic materials. For example, compare reading something on white paper vs the solid white screen you are looking at right now. Paper is a lot easier on the eye and one of the reasons is that if you look real closely, you'll see that it is not pure white but it has complex texture.

I would also like to see icons that look like they were painted with real paint instead of over stylized clip art with no real soul.