Not putting so much focus on the clones. I think the Clone Wars are mentioned twice in ANH but I always took it was one of many wars that Anakin and Obi-Wan could have fought in.

Seeing an army of Temura Morrison's and the minor mystery of who ordered their creation didn't catch my interest at all. There's no mention or sight of any modern day clones in the OT so it feels weird to see such importance placed upon them in the PT.

Having a recurring villain in the PT would have helped it a lot too. Having a new arch villain in each film didn't work well. Darth Maul is cool and mysterious but that doesn't go anywhere because he gets killed.

Count Dooku is kind of interesting at first because he's initially portrayed as this character who is in the middle of battle. He believes the Jedi are corrupted, but he also fears the Sith and this Darth Tyranus guy...but then it turns out he is Darth Tyranus and he was just BSing Obi-Wan. Also, I get Lucas is going for meta symmetry with the OT and PT by having the Hammer version of Van Hesling and Dracula but I think that's a poor excuse to to cast Christopher Lee as a Jedi/Sith and all him "Count." Takes me out the movie for a minute.

And I never would have put in a cyborg Sith with breathing problems as a villain in the same movie that Anakin becomes Darth Vader. Darth Vader is supposed to be unique, so it takes a little bit away from him when you see a proto-Vader just before.