The expected effects (especially with polarization filter) are very clear and you do as a novice fast success with great photos.
However, falls on when looking at the PC: The sharpness of taking photos with filters sharply, gradients are apparent in the wide-angle one sees shades of the adapter to the image corners.
My Conclusion: Stay away, unless you want to try only. Better a few euros more to spend on a high-quality filters and shallow adapter ring!