e.
I felt it was underwhelming and didn't do good damage. But then I watched vids and tips online to the point where I felt the best style to use destruction.
The trick is to have low health for the player, and a huge amount of magicka.
Now, you may be thinking "what does that have to do with damage output?"
The thing is, by playing with low health, enemies have the potential to do a lot of damage to you easily. If you have a mage with a lot of health, enemies take too long to kill you, so you bump up the difficulty to master/legendary, where it takes too long to kill anyone.
If you play on a lower difficulty with low health, you can dish out more damage to enemies because of the difficulty, while they can do the same to you.
I am currently playing a lv64 dunmer mage, with 960 magicka and 130 health, on expert difficulty. He has 100 in all schools of magic, and I have to say, its fun doing large amounts of damage to enemies.
And its not to the point where you one shot everything either, expert difficulty is good enough that it takes some time to kill enemies, but not too much time.
You don't die a lot either because a mage is supposed to keep his/her range, which is why spells are cast from a distance.
Also, if you have dragonborn dlc, whirlwind cloak is a must, makes any melee enemies easy prey