I've leveled to 100 in destruction magic, and I can say without hesitation that I was massively disappointed with the magic in skyrim. Magic doesn't seem to level with your character, so once useful spells become completely worthless by the end, and more powerful enemies will always take at least half a dozen attacks, even on the easiest difficulty.
For those who haven't reached the higher levels of the destruction tree, at one point you get a fire spell that creates a massive fireball exposition with a 15 foot area of effect. Then that's replaced by a more powerful spell that has no area of effect, and requires a direct hit. Then THAT is replaced by the most powerful fire spell in the game, which requires a completely ridiculous number of magic points, requires BOTH HANDS, requires that you stand perfectly still when activating it, and--worst of all--it's not even a projectile. It explodes outward from you body, and STILL usually isn't enough to kill all but the weakest enemies by the time you are around level 50. The highest level lightning spell is a little better, but it still requires you to use both of your hands, and stand in place the entire time you're using it.
Meanwhile, I can drop almost any enemy in the game with one or two stealth arrows, or simply sneak up behind them and stab them once with a dagger.
Destruction magic sucks.