I've been practicing throwing back grenades, and I really like the mechanic. It takes skill, sometimes luck to throw back the grenades unlike in other games with that feature.
The problem is, I've noticed the throwback grenade button gets overridden by every other action that required the triangle button, namely picking up ammo or guns (or grenades) and the most annoying, healing a team mate in co op, resulting in you and your friends death.
They really need to fix this. It's bugging the hell out of me now that I have come to use this mechanic frequently. --- Combat PC game piracy by making only really bad console ports to lose less money. Combat bad console ports by pirating the games instead of funding them.