i tried shooting mine into a few water bottles, soda bottles, and the odd over- ripe watermelon. i've never run my load over a chrono, but i would estimate that the 'whompability' is about that of a .38 short, or perhaps a bit better.
not a one- shot- stopper, but certainly not something you want to stand in front of. for antipersonnel work, i'd grab something in a larger caliber (either ML or centerfire)
you want to let a lot of blood out and a lot of air in. shoot straight, shoot first, and shoot again (in exactly that order) repeat as necessary; you don't get extra credit for style, and the notion of 'ammo conservation' is vastly overrated.
that's the end of the tirade and, as is the case in many of my tirades: free advice and worth every penny.
just one guy's opinion...