Whilst platform is viable with gyro's or computer aided flying if you wish. How much kickback can it handle - could you actually fire a gun from this? But certainly does negate many of the aspect people have against armed drones as this is in effect a human drone.
But it is pretty neat, as many recall the facination with jetpacks and the dreams that we would all have them in the 60's/70's (along with flying cars), so this kinda ticks many box's of past dreams.
As for distance/flight time - kerosene is pretty dense energy wise, and I can't think of anything else that would be as flexible and offer greater energy density. But still, if you compare this to jetpacks - very impressive.
For me one use case for something like this may well be firefighting or certainly a way to escape a tall building that is on fire from your flat balcony.