The 5.7 is very similar in woundinding ability to the 22 magnum. I have fired one, and found it to be accurate, as far as practical accuracy, not bench rest type accuracy, fast repeat shots, and very little muzzle rise. I also came back into battery very quickly, which is important to experienced shooters.
I doubt that as far a fifty yard shots on rabbits, it would be any more accurate than any other "service" type pistol, which is to say it wouldn't work for that purpose. The main constant in putting down an adversary in an armed confrontation is shot placement, and it's dependent cousin, penetration. It would seem that any round that would penetrate light body armor would pass all the way through a human body; not so. The military and service rounds for the 5.7, as well as a similar Chinese effort are designed to tumble shortly after imopact, usually around five inches. After this point, their paths are unpredictable, and penetration is very shallow. With commercial ammo, expansion causes the lightly constructed bullets to lose their jacket and go to peices(they are designed to do this, for varmint hunting). Their penetration is worse.
These small caliber, high velocity rounds can certainly kill, but it would take a lucky shot in a defensive shooting. I have killed many hogs that we raised on the farm for meat with a single .22 long rifle to the head, but if I go hunting, I always take my .44 magnum.
With all this said, everyone can't handle a "major" caliber weapon. They should carry the biggest caliber that they can hit effectively and repeatedly with. The 5.7 certainly has a place in this scheme of things. I would feel far better armed with a 5.7 than I would with any "pocket rocket" that i have ever fired, because I can hit VERY effectively with it, and very fast. The gun, and it's feel in the hand is far more important than caliber, but by the same token I still carry a 44 magnum myself. I can hit very fast with it, too, and it is exponentially more effective, more along the lines of a medium bore rifle than a handgun. The 5.7 is very similar in wounding effect to a 22 magnum, or a 22 long rifle. I hate to say it, but a good hi velocity .22 may well be better, because of the supeior penetration.
By the way, the trigger AND the controls suck.