That doesn't look awful, although it doesn't look particularly promising, either. However, this is the description:
From Disney comes "Maleficent"—the untold story of Disney's most iconic villain from the 1959 classic "Sleeping Beauty." A beautiful, pure-hearted young woman, Maleficent has an idyllic life growing up in a peaceable forest kingdom, until one day when an invading army threatens the harmony of the land. Maleficent rises to be the land's fiercest protector, but she ultimately suffers a ruthless betrayal—an act that begins to turn her pure heart to stone. Bent on revenge, Maleficent faces an epic battle with the invading king's successor and, as a result, places a curse upon his newborn infant Aurora. As the child grows, Maleficent realizes that Aurora holds the key to peace in the kingdom—and perhaps to Maleficent's true happiness as well.
Ack, no. What is that? That verges on abomination. The whole force of Maleficent's actions was that she cursed a girl to die and doomed a kingdom to the disaster of having no succession simply because she wasn't invited to a celebration, and then vanished laughing with delight. She was a fairy, in the old-school sense, in the sense that Susanna Clarke captured in Jonathan Strange & Mr. Norrell, in which the fairies have no sense of proportion and are ruthlessly logical in their massively disproportionate responses to everything (and also utterly delighted in the effects of the disproportion; it's notable that Maleficent is constantly laughing in delight at all the very bad things she is doing). Then, and this is in some ways just as evil, she locks Prince Phillip up, shows him the girl he's in love with and who loves him, and taunts him by telling him that she will keep him locked up until he is so old that he is about to die -- when he can finally go and see his true love, who will not have aged a day, and then laughs at him. (It's a remarkable scene: she shows that she knows she's in a fairy tale and she has decided to rewrite it as an anti-fairy-tale.) Then when he escapes, she raises the forest of thorns and, threatening Phillip with all the powers of hell, becomes a dragon like the devil she obviously is standing in for. And, indeed, she is so powerful that nothing can protect you from her except something called the Shield of Virtue, and she can't be killed except by something called the Sword of Truth. ("Sword of Truth, fly swift and sure, that evil die and good endure!")
Remaking that story as an attempt to get revenge as a result of a betrayal is like remaking Paradise Lost as a story about a young man who, protesting what he sees as the mismanagement of his powerful employer, leaves the company and starts his own business, getting involved in some shady dealings along the way. This might make an interesting story, but you don't try to tell it as a retelling of the Fall from Heaven.
And it's a difficult thing to do, already. Angelina Jolie apparently really likes both the original movie and the character, so she might salvage a lot, but it's difficult to see her pulling off the intelligent, gleeful, ruthless elegance with which the incomparable Eleanor Audley conveyed menace and smooth, smiling malice in almost every tone.