I too really like how the two colors work together. As stated previously, the nib flair is a nice touch. My only criticism in design would be that I think the two finial accent pieces are a bit too large. If they were reduced by say, 40% or so, they would look more like decorative caps rather than large, heavy accent pieces.
It is something to consider in the future, but my first impression of this pen was "Wow!" so I think you've got something special there.