It works well on just about all fire using enemies and my "pure mage" finds using ice spike and ice storm especially useful for slowing down charging enemies in certain situations. I really quite like it and if used properly it can be a great asset in tight situations.
Dual casted Ice Storm in a corridor, and it doesn't matter if you're 50% resistant to frost
Ice slows down enemies and decreases their stamina, so i use it against melee fighters. Many of those are nords, but those effects apply to them regardless.