People give this a bad name without trying it. It is brass cased and has a hybrid polymer/copper bullet. The idea is to get a super light, high velocity bullet that does more damage than ball, without the under penetration of hollow points in smaller calibers and short barrels.
With that in mind, this is a great idea for .380 mouse guns and anything with a short barrel. The only thing this fails at is barrier penetration. I question its usefulness in bigger caliber as they already get high velocities , but in the small stuff it seems to have real potential.
I know this is expensive, but it is marketed as self defense ammo, not plinking ammo. I have never seen cheap self defense ammo. It definitely deposits more energy in the target than ball.