Does what it advertises. Optics appear clear. Filter rotates smoothly to align dividing line. The one I purchased is the lighter version and it works well for retaining detail in medium high contrast situations without being too obvious where the horizon line is not well defined. Could well give it 5 stars but I'm conservative.
This filter is very useful for reducing overexposure of the sky in outdoor photography. With only one stop of compensation you may find it is not enough effect to completely eliminate overexposing the sky under some conditions.
It is hard to see the effect of the graduation in the viewfinder of my D200. I found that I needed to mark the filter so that I could easily identify the darker portion of the filter and get proper placement of the darker area consistently. A marking form the factory would make this much easier.
I highly recommend this to get better expose of the sky in outdoor photography.