NAA has a ballistics page here: http://www.naaminis.com/magvel.html. I've never shot anything with one of these guns, even a piece of paper, but the ballistics aren't exactly encouraging, being less powerful than .22LR out of a rifle. That's pretty low on just about anyone's scale.
On the other hand, having the NAA does fulfill the First Rule of Gunfighting, and is better than fingernails. Whether it is better than a sharp stick is open to debate.