Bought this filter on the back of Philip Bloom's own video on his YouTube channel. I bought the 1/8 filter for my Lumix 50mm f1.8 and it works as advertised. Lovely blooming around light sources to make them look less digital and more filmic and my lens definitely hasn't lost any sharpness. Losing harsh sharpness on faces has also been beneficial.
Not perfect though. At night, some extra refraction will sometimes give extra reflections in your imagr, especially noticeable at Christmas and if you're trying to shoot at an angle to the light.
The other problem I had was during a rainy shoot. I was drying the filter often with a circular motion and managed to unscrew the little ring that holds the glass in, so it fell apart! Not sure if this was because it wasn't fitted perfectly with enough force at the factory or whether I was just too exuberant with my cleaning. The glass fell out and onto the ground mid-shoot! Managed to piece it together though and continue. Thankfully, only one minor scratch occurred.
The filter does look great on the end of the lens... I went for the gold version and it looks like a little gold crown 😂 Gives my S5ii the King status it deserves 😉
Overall, would definitely buy again. Just be careful cleaning it!