I use a CPL filter when shooting landscapes, but I also wanted to add a black mist filter for videos. I was worried about vignetting at the wide-angle end when using two filters stacked on top of each other. Since I started using this filter, that problem has disappeared, and I've found myself worrying about the filter less while shooting.
The CPL filter works naturally, with almost no yellow cast, which is common with cheaper filters. I could definitely feel it reducing reflections on the water surface and bringing out the blue of the sky. The black mist filter's effect is subtle, only softening highlights. Since it doesn't create an overly soft effect, it's perfect for any situation.
However, since it's a 2-in-1 filter, you can't turn off the CPL and mist effects separately. At night, when I want to use only the mist filter, the light level drops, which can be a bit of a problem. I have no complaints about using it specifically for daytime outdoor photography, but I feel like it would be difficult to use the same filter for night scenes as well. It might be more practical to use it in conjunction with a standalone mist filter. The coating feels firm to the touch and is easy to wipe off dirt.