The biggest problem would be explaining the Multiverse to the uninitiated. They've got to cover mana, spellcasting, planes, and Planeswalking. That could potentially be quite a bit to fit in, which could bog down the story. Unless they decide to just ignore all that Planeswalker stuff =_=
I think people get "people can cast spells and do so by drawing energy from the land" and "some people can teleport between different dimensions".
At the very least, I don't think they have any more expositing to do than your average spec fic film. Thinking of ones I saw last year alone,
Epic,
Pacific Rim,
Thor: the Dark World, and
Frozen all had get out at least two big, important concepts as difficult as Planeswalkers and Mana. Your average 1-hour episode of
Doctor Who likely introduces as much, and first episodes for a particular companion (like "Rose", "Smith and Jones", or "The Eleventh Hour") usually do more as they have to introduce The Doctor and usually the TARDIS.
EDIT: Hell, let's try to do this. Taking a noncommittal scenario and trying to get the exposition out of the way as fast as possible
Chandra* (Voiceover narration looking at generic stars-and-false-color-nebulas arrangement): Dominia. The Multiverse. Countless worlds strewn across the Blind Eternities, largely ignorant that the rest of creation exists beyond their borders. I am a Planeswalker, one of the few gifted with the power to travel between the worlds of Dominia... but that doesn't always mean life is easy.
[swooshy zoom in onto a random point of light to cut to...]
YOUNG CHANDRA attempting to cast a spell. after a moment it fizzles out with a pop and singes her fingers
YOUNG CHANDRA: Ow! [shakes hands]
MENTOR: Focus, Chandra. The power to call your magic, and control it, is all around us. In these mountains [pan out]. Feel the fire within them, draw on that, and the fire inside you will be easier to manage
YOUNG CHANDRA: Is that why we're way up here? Can't we do this at home.
MENTOR: Other lands have other powers. The high mountains suit you best. Plus, you wouldn't want to set your house on fire, would you?
[Scene continues to a point, blah,blah,blah]
Seriously, just crud off the top of my head here. Expositing is not hard.