First acquaintance with this was a guy shooting one on the range, a combination of a roar like a .44 Mag but the pistol barely moved in recoil. I watched a few shots and said "I don't know what he's shooting, but I want one." Few days ago had the chance to fire a magazine through one.
It uses a double-stack mag full of these, so that's 17 rounds of roar. HUGE muzzle flash, loud as a .44, and very little recoil. Very vigorous ejection, but we did find all his empties. Couldn't save the target, but at about ten yards it grouped nicely.
Bit of searching turned up some gel tests, which looks like this would definitely do some damage.
And yeah, I want one. Especially since it comes with a 9mm barrel and recoil spring and you can use the same magazines with both cartridges.
*Picture from the Armscor site