IMO it's worth watching the video rather than reading someone's writeup of it. My favorite part is this (written) list of everything that went wrong [1] ... and how much of it is due to the intersection of hardware, software, vendors, and linux
I don't even like carrying the smallest of folding umbrellas around in case it might rain. Then if it does, this thing will hover so far above and away that you get wet anyway optimistically saving up to 50% of raindrops. 50% wet is still wet. If I have an umbrella I hold it close over my head unless I'm covering someone walking with me.
50% is very generous. In the video it isn't even consistently above his body half the time. It is also constantly a good 80cm above him, so even a slight bit of side wind makes it fully useless to keep you dry.
Any wind speed above 20m/s is also going to just blow it straight out of the air or at best heavily reduce flight time.
And then there is the little issue with having a mini lawn mower constantly above your head: loud and dangerous.
Having said that, we can still applaud the creator for bringing their idea to life.
I don't even like carrying the smallest of folding umbrellas around in case it might rain. Then if it does, this thing will hover so far above and away that you get wet anyway optimistically saving up to 50% of raindrops. 50% wet is still wet. If I have an umbrella I hold it close over my head unless I'm covering someone walking with me.