The 5.7 is fairly speedy
for a handgun round but doesn't "set the woods on fire" if this link is to be believed. The column showing the lower velocities is realistic as the ballistic figures in the other column were generated out of a custom 22-inch barrel.
http://www.gunsandammo.com/content/57x28-fn
The .22 Magnum fired from a rifle for comparison. Found within this all-encompassing .22 rimfire ballistics chart. My chronographed velocities of various .22 Magnum ammunition fired through my dad's rifle correspond closely to these figures.
http://www.ruger1022.com/docs/22lrballistics.htm
The .22 Magnum fired from a rifle whips the 5.7 fired from the handgun. The 5.7 won't be any more magical in performance than a good .22 Magnum rifle on critters. It also wouldn't be expected to offer anything special against human targets that
any decent round can't offer, assuming good hits.
Clever in a way, the 5.7X28 is also a bit of a yawn.