I've owned three different Auto Ordnance pre-kahr Thompsons.
They were very accurate, and totally reliable .
They COULD be used for home defense, (there are people who use the Colt Single Action Army as a defense gun). However, they are really a nostalga item, like the Colt SAA, the Winchester 1873, and the very early 1911 Colt autos.
If any weapon was overbuilt, it was the Thompson. In these days of aluminum and plastic, it's still milled steel and American walnut. I view it as a prestige and sheer nostalga gun. Since most of us aren't allowed full auto weapons, and couldn't afford them in any case, this is as close as we can get.
Plus, their just plain FUN to shoot.