It's not a huge problem, but sometimes the enemies don't react to being gradually killed. Not when I stand a little way off, anyway. But I don't have to be behind cover; I could be clearly visible - perhaps elevated by an old truck or boulder. And they will just accept the fire, stoically. [Check out the (very poor) vid.]
Dear Bungie, is there time to fix this before the full game launch? If not, it's no biggie, though.
Love,
~ scarytiger.