It was a dreadful mistake to base all three of the prequel movies around the fall of Anakin Skywalker, largely from the perspective of Anakin Skywalker. It might be strange for people growing up in a post Game Of Thrones era, but as a society we generally do not allow the creators of fiction to get away with insufficiently condemning the villains that they create. Back in my day people would shit the biggest bricks if stories didn't at least implicitly promote either Christian or secular humanistic values, much in the same way as the social justice brigade will haul you over the coals for failing to adhere to their own byzantine politics. The mob rarely trusts creatives to create or illustrate work that portrays acts of wickedness in a non-judgmental fashion. So creatives whose livelihood depends largely on the patronage of others seldom take the sort of risks that might incur the wrath of others upon themselves or their patrons. While House Stark might be terminally stupid, they at least do not make a habit of crippling children, fucking their own siblings and mistreating their (very) likable sons simply for the crime of being born a dwarf. The author makes it abundantly clear that he condemns his villains to his audience, even as he begins murdering his way through the cast starting off with the characters that he had setup to be viewed as the traditional heroes of the story. So with this in mind, it is very, very hard to write a fall from grace that is simultaneously a rise to power without making your antihero either an unlikable ass, or appearing far too sympathetic to the villains and what they're supposed to represent to your audience. Because generally an author doesn't want to be seen as looking too sympathetic to villains that they themselves have admitted to basing off Nazi Germany.
So the implacable and terrifying Darth Vader who was once willing to mutilate his own long lost son both physically (by cutting off his hand) and mentally (by repeatedly trying to turn him to the dark side) so that he can challenge and defeat his own master becomes Anakin Skywalker. A creepy sexpest of a child who never quite manages to grow up and mature into a fully functional adult, and whose career as a Jedi Knight is marked with repeated instances of stupidity, general incompetence and outright failure. With a good scriptwriter and good actors you can make a good film out of anything, but that there is an uphill battle if I've ever seen one.
Personally I think that they would've been better served by creating a new main character who could function as the audience surrogate, only to have them be betrayed and killed off by Anakin Skywalker towards the end of the third movie right before the climatic battle that almost destroys him and turns him into Darth Vader. It seems to me that George Lucas attempted to do this with the character of Padme Amidala, but in my opinion he failed abysmally. By the time it happens her character is little more then a plot device and it has been at least a movie and a half since we saw her doing anything even remotely entertaining. If you want to see a good example of doing this sort of thing properly watch Django Unchained and keep an eye out for King Schultz played by Christopher Waltz.
On second thoughts, maybe I would roll the role of Padme Amidala into that of a female Jedi who gets tempted and corrupted to the dark side by a wild, powerful and tempestuous Anakin Skywalker. Who nevertheless convinces her that he can keep a lid on it and bring balance to the force because he is the chosen one. After she gives birth to Luke and Leia they confront the Emperor together, who manages to turn one against the other. Anakin defeats and kills her, and tracks down Obi-Wan Kenobi seeking to reclaim the children who were left in his safe keeping. Cue the duel on Mustafar, but with less waffling about having the high ground.