Well, as long as they're not wearing body armor sufficient to stop the round, poke enough holes in them and eventually you'll get to something vital. And in most places, you can poke a lot of holes in someone with that gun, and pretty quickly.
Absolutely. Hell, I wouldn't warn somebody off from, say, a hundred year old .32 pistol, if that's what works for the user. In the overwhelming majority of defensive gun uses, just _having_ a gun is enough to make the attacker realize he has someplace else to be. I'm just saying, if you have over a thousand bucks to drop on a defensive handgun, a 9mm of some kind will probably do the job better, hold just three or four fewer rounds, have only marginally worse recoil, and not use an expensive boutique cartridge that will probably be a collectible in ten years. If a body has the money for it and loves the feel and light recoil of the Five-seven, mazel tov. It's certainly not a toy.
I keep forgetting about the price tag. Yeah - I'd rather have 2 or 3 Glocks than 1 FiveseveN... Hell, I'd rather have however many of that .22WMR Oleg's gone gaga over (with 30 in the mag) that 1 FN at that price. Or even a couple of P22s
Or, for that matter, a Glock, a year's membership at a range, and a generous pile of 9mm ammo (or one of those .22 mags plus a lifetime's worth of rimfire ammo). For a defensive gun, I'd say ammo and practice are a much better use of the gun budget than the Five-seven's mixed plusses.