How does it work exactly? I mean is it basically a bullet-proof vest only a lot thinner because Marvel-Sci-Fi-Magic? So bullets wouldn't go through but the impact would still leave a bruise? Would it be the same with knife-attacks (if the knife hit him with enough force) or would that be absorbed completely? How about normal punches?

tl;dr: what kind of injuries will Matt still have once he's wearing the armour? What will he have less of? (What do the comics say on that subject?)