I understand the criticism of this movie. The lip synching was indeed terrible. And the writer and director did Callas a personal disservice by focusing on this part of her life, when she was crazy and high and alone. But I don't believe a biopic has a responsibility to show a person's entire life. It can show a portion, if meaningful and true - which this was, even if it was unflattering. The sad decay of a brilliant life is a story worth telling, and this was told with tenderness.
The flashbacks could have added more value and depth by following a linear plot, showing the arc of Callas's career, her great love story and the many sides of her personality. They could have done more to educate viewers about who she was, the complexity of her character and her artistic process. But the director chose instead to play her life back as her own mind might have in those last few days: fragmented, intense last gasps. We see her grapple with pride and regret, asking herself if it was all enough. It's as much a movie about the act of dying as it is about her, and for that I found it beautiful.
Jolie did better than I expected, and I even think she looked like Callas in the black and white scenes. Too beautiful, but Jolie possesses a similar woundedness that translated certain elements sufficiently. While she captured Callas's tortured and demure sides, she did not capture her charisma, temper or ruthless perfectionism. It was a valiant attempt at a role no one could have played perfectly. Callas was untouchable in life, and knowing she still is in death made me love her even more.
In short, the movie was imperfect but its intention was sincere. A deep love for Callas came through that made it worth watching, if you can focus on the story being told instead of the story you wish were being told.