it's pretty pedestrian up until you get the ammo return perk, but once you get that? You're hitting with virtually 100% of ammo used, so if you just use it specifically in sections where you are facing lots of enemies at a close range, it's super effective. I crush Hive Wizards with it (doesn't matter if they dodge my rounds, those get returned, I just re-adjust my aim while still firing), I sweep waves of Fallen or Vex. It's not great on bosses, but that doesn't mean it doesn't have utility.