It's hard to say how many of the negative experiences other reviewers have described are due to the product, and how many are due to incorrect use. When I hold up and rotate this slide, it does exactly what I expect it to do. For example, reflections on a window disappear and then reappear when I rotate them at different angles. It simply works well!

I suspect that some of the reviewers did not pay proper attention to the direction of polarization. To do this, position the film where you want it to be used and rotate it until glare from the problematic light source is minimized. Then apply the film exactly at this angle and make sure to remove the protective films from both sides of the film. There are two protective films!

Note that such a polarizer only reduces reflections from surfaces that are tilted away from you. The reflection that you see of yourself, for example, will never disappear as a result, because if you can see yourself, the surface must be parallel to you.

Polarizers also do not help reduce glare on metallic surfaces because these surfaces do not polarize the light reflected by them.