Though its casting cost is greater than that for a Flame Atronach or Frost Atronach, it allows you to save time by both getting rid of an enemy and getting help to defeat the remaining ones. If your enemy summons a Storm Atronach, you'll need to dual-cast the spell, since Storm Atronachs are level 30 - too high for this spell if single-cast. This spell does not work at all on Dremora Lords. If your goal is just to get rid of your enemies' summons, Banish Daedra and Expel Daedra both have a lower casting cost. Additionally, the Oblivion Binding perk for Bound Weapons allows you to banish Daedra on strike.
If the enemy that conjured a daedra has the Atromancy perk (doubled duration for summoned atronachs) but you do not, once you cast this spell on the atronach, they will still last 120 seconds, even though you do not have the perk.