Better than harsh words and a stern look, I suppose, but as a firearm,? -- a joke, designed to separate rubes from their money.
Awful human engineering by nature of the design -- can't get a decent firing grip, so even if the guns were accurate, it would be hard to hit with them. The couple I've tried had radically different points of impact for the two barrels (like a foot or more apart at 7 yards), neither of them bearing any relationship to where the sights were aimed.
Recoil is vicious, yet the stopping power of .410 out of a short barrel is nil. Friend of mine got shot in the face last year, at close range, by a robber with a .410 sawed-off shotgun. His bell was rung, but he was not killed, knocked unconscious, or incapacitated. Had the punk not run away immediately, my friend would have killed him. Despite a face full of pellets, he was still capable of drawing and firing his .45, had the target only stayed around a couple of seconds. That's not "stopping power." My friend has a hell of a nasty scar on his jaw, but that's all. (Punk got away, never caught.)
Although the .410 derringers are small, they are not all that light.
If you need a desperation gun that is easy to hide, get a Kel-Tec .32 or .380, and practice head shots. A titanium 5-shot .38 is a little bigger, but still lighter. The .410 O/U derringer is the mark of a duffer.