Ability to cast 2 spells at once.
Ability to combine 2 of the same spells into an uber powerful version.
Multiple ways to obtain spells. Buy from mages or find in spell tomes.
Dragon shouts unique to the player. So you can now cast 1 spell, another, and then a shout! boom boom boom. Sounds like a pure mage could be more powerful than ever now.
You can learn magic by dienchanting items.
There are perks which will enhance magic.
There are more than simple touch or projectile spells and self spells now. There are constant use (fireballs are now flame throwers), projectiles, probably touch, self spells, area affect spells which make traps, chain spells (lighting bounces around corners, how cool), the clairvoyance spell which lays a path for you, and obviously a ton more they haven't shown. It's clear that each spell has a real use now, where in past games frenzy never worked, burden certainly failed every time, and really there was only a small handful of useful spells. Now it looks like everything I've seen is clearly effective in a different situation.
In retrospect the magic system looks way cooler than it has ever been. Stop focusing on what they took away and start dreaming about the possibilities of what are NOW possible.