Just this actually, Padme shouldn't have to die too soon. It makes Leia's scene, when she said to Luke that she remembered her mother's appearance in ep 6, weird. Plus, I heard that the writers originally wanted her as one of the founders of the Rebel Alliance and fought the Galactic Empire. Wife v Husband: Dusk of the Force. It will be cooler, eh? XD Also it will make Padme a stronger character in ep 3 than she is now.

They ruined Vader

It's not so much that they ruined Vader's backstory as it is them trying to fit all of his complex personal issues into three movies. #1) He doesn't become a Padawan until the end of the first episode. #2) He's already giving in to the dark side by the second episode after his mother gets killed. #3) The prequels only show the beginning and end of the clone wars with the third episode only showing the last days of him being a Jedi Knight and no longer a Padawan, therefore making Anakin's turn feel "rushed". That's probably why The Clone Wars series was made which takes place between Attack of the Clones and Revenge of the Sith. It probably would have been better if they labeled the original trilogy 5, 6, and 7 and made the prequels into 1, 2, 3, and 4, making it a quadrilogy. And 3xZ, it is possible to remember things from infancy, just extremely rare. Plus, like Luke, Leia had a Jedi father making her Force-sensitive even if it's only to a small degree.

I think if they had nailed the Anakin/Padmé love story in Ep II, I think the prequels would have been perfect.