I feel strongly that, if you are doing the secret history / flipside of Sleeping Beauty, you should hit more than one plot point from the movie! Actually, thinking about it I suppose there were three plot points in common -- the christening, sending the baby off to live with the three good fairies, and Aurora and Philip meeting in the woods. But only one of those was part of Maleficent's arc. Where was Maleficent tormenting Philip in the dungeon? Where was Maleficent battling Philip at the castle at the end? WHERE WAS MALEFICENT TURNING INTO A DRAGON? TURNING THE BIRD INTO A DRAGON DOES NOT COUNT. (It was a very pretty bird-dragon, but it was THE WRONG DRAGON.)
And that christening scene, the one scene they got basically right, they dropped the third fairy all over the floor. The first fairy gives beauty, the second gives happiness (also, "she shall be happy all the days of her life"? THAT IS NOT A GIFT. THAT IS THE CURSE OF INAPPROPRIATE EMOTIONAL RESPONSE AND THEY SHOULD HAVE PLAYED IT MUCH CREEPIER THAN THEY DID.), the third starts to say something, Maleficent interrupts, you get the whole curse thing, Maleficent goes away, and THEY COMPLETELY FORGET ABOUT THE THIRD FAIRY. THERE IS NO THIRD FAIRY GIFT ANYWHERE IN THE MOVIE. I thought maybe they were going to come back to it later in the film, perhaps save it up and then bestow it after Aurora falls asleep, in a sort of Chekhov's gun style surprise save, but no. They just forgot.
I did like the godmother's true love working. I thought that was very nice. But I wish Philip had had a bigger part anyway. He didn't need to have any agency or really any more lines, but I thought he was underutilized. (Although literally being towed around unconscious was funny.) Some kind of ruse where Maleficent and Philip working together to rescue Aurora looked visually like the Maleficent/Philip battle in Sleeping Beauty would have been great.
Also the worldbuilding didn't make any sense. If the Moors had neither king nor queen, why did the land turn dark with Maleficent? How could the restored Maleficent crown Aurora queen of both lands? It just didn't work on either a realistic or a fairy-tale level of stylization.