I got this thinking it was a typical ND filter and completely skipping over the black diffusion part of the description. So I was a little surprised when I put this on my camera and all of a sudden my video looked soft.
The black diffusion part of this filter adds a special effect of softening the footage to give it a dreamy look. It's akin to stretching a thin, mostly see through piece of fabric over your lens. Except this filter gives you a far more consistent and easy to work with image. The black part of the diffusion adds darker overtones to what is otherwise a dreamy image. The example photo in the images really captures it well. If that's a look you like or are going for in your image, then this lens is fantastic.
I did play around with trying to remove the look from the image. The softening effect means you'll need to shoot much higher resolution than you are delivering in in order to sharpen the image without making it over processed. Even then, the dark dreamy look never entirely goes away. So I would recommend only using this filter when you're wanting that type of look.

The ND part of the filter works really well. The different stops are clearly marked on the edge of the filter and it clicks into place nicely. Adding the ND filters gives you so many more options for shooting wide open while in bright light without having to use a ridiculously high shutter speed.

If you're looking for a pure ND filter, this isn't quite it. But if you want an ND filter with the black diffusion to achieve a specific look, this is the easiest and best way to get that effect that I've ever seen.