Modern cameras with good optics produce crisp, sharp photos. You can see every detail here.
No crease, scar, or impurity remains hidden here.

Especially when you want to photograph portraits, this wealth of detail is not always wanted. Unless you want to highlight the wrinkles, etc. as an artistic device.

But if you simply want to create beautiful portraits, this filter can be used. It mitigates precisely these weaknesses, if you can say so, and produces wonderfully soft - though not blurry - results. The contrast is also reduced, which simply creates more beautiful photos from hard and cold light.

The filter I have has a strength of 1/4 and is therefore the second weakest. All the effects mentioned above are therefore present, but not so strong that it appears artificial and perhaps even kittish.

Sure, you can now say that such effects can also be done in post-processing, but this filter saves you a lot of work and has a more analog workflow that I personally really like.

In any case, the filter has already proven itself and is more than worth its - low - price. Especially since there are three good cleaning cloths as a nice bonus.

I can't identify any negative points, so I can give it the full five stars here.