Sorta like having your very own hand grenade.
I must admit, if offered the chance, I would shoot it. Just to say I had done it. OTOH, I figure the slug has to be right at the end of the bore, so there probably isn't a whole lot of pressure built up.
I'd love to see figures on the velocity vs. something with a barrel.
I'm amused that American Derringer calls it something like the Alaska Survival Gun. Other than the noise, a long knife would probably be more effective against a bear. And a .22 would do as well against card sharks.
-----Paul------