I haven't bought one of these but I might someday, just for the hell of it. For right now, I spend my "gun stuff" budget on ammo and classes.... handgun classes, because as I told a buddy last year when he asked why I never want to take a carbine class with him, "We aren't soldiers any more.... If I ever have to shoot anyone again, it will most likely be with a pistol in a parking lot somewhere."It's hard to argue against that point -- except in that it pre-supposes the fact that you've hit the guy, quickly enough, accurately enough. And for that I'd reach for the handgun every single time. But everybody's got to get to the range on their own and assure themselves of sufficient capability in that regard.
And if I do buy one of these, I would take it to a defensive shotgun course and run it against the stocked guns to familiarize myself with it's limitations. The only thing this has going for it IMO, (other than "cool factor") is the same thing a handgun has, it's more portable. It's a niche weapon that delivers a lot of close range power and is only useful in a very narrow set of circumstances, and only to people who have the upper body strength to use it well.