While I loved them, being what I grew up with, I can still find fault in them.
Probably the biggest one is the way Anakin was acted.
And no, it's not because Hayden Christiansen is a bad actor, I actually thought he was quite good. I've re-watched them all multiple times and I never see any bits where I cringe or go 'Ooh shit, that was bad'.
It's because the character was wrong.
He was well acted (In my opinion), but he was acted as an emotionally invested, love-dependant character.
This therefore made the way he suddenly changed to the dark side all the more wrong, and while I mention it I think that was done badly too; There's one thing switching sides to save your wife, another is forgetting your entire moral code that you've had your whole life and slaughtering children.
In my opinion, Anakin should have been, instead of secretly wanting forbidden love, actually secretly desiring forbidden power, and instead of Palpatine trying to convert him by manipulating him into doing it for fear of lost love, instead turning him to the dark side by convincing him that the Jedi don't have the balls to lead the galaxy to a peaceful future, and that the dark side potentially could.
I think this would be better because there is little actual reason other than Anakin's hurt pride at not being a Master to make him hate the Jedi Order, making it quite unbelievable when he suddenly is willing to kill them all.