I have had my PhantomFilters for about two weeks now and have used them on several flights. I am not a professional photographer, not even a good amateur one - but I am trying to learn.
Pros -
Lightweight gels that easily slip into the Phantom UV lens cover
4 different filters - ND2, ND4, ND8 and ND16 - that can be used based on the current lighting
Cons -
I have had difficulty removing the filters and have had to use a finger to the center to get it out - so will be looking for a way to clean my fingerprints off of them.
For the price, you can't beat this set of filters. They perform exactly as expected, cut down the light entering the lens and allow you to set the shutter speed lower to reduce/eliminate "jello". They really are a good deal.