The problem with the prequels was the George Lucas lost his touch. He was surrounded by more talented people during the original trilogy that pushed him to make the movies in a way that he did not want to, but in the end were far better. The experience of making Empire traumatized him so much that he eventually cut off ties with most of those people and when it came to Jedi, he just remade Star Wars, only this time with little teddy bears and some old man wizard of an Emperor.
Then, Lucas has about 1.5 movies worth of background material for the prequels, and since he needed to do a trilogy (thanks to inexplicably attaching EPISODE V to the scroll of Empire Strikes Back) he had to screw with the back story so much that it hardly made sense anymore. And it is just so stale.....
What happens in Phantom Menace? Seriously? Anakin is found on some desert planet. the rest is just filler.
What happens in Attack of the Clones? Nothing. Its all just filler and garbage. The whole thing seems to be an introduction of the Fetts and how they are related to the clones, which in the end is completely dropped.
Then finally we have Revenge of the Sith. Which Lucas had to squish all his backstory into because he did such a bad job pacing out the first 2 movies, and as a result Anakin's transformation is so quick it is almost instantaneous, as if they guy only got the job of Jedi a week ago.
and the acting......the acting is just so bad, the dialogue so brutal. Watch a Star Wars prequel and then watch Serenity. When compared to other work in the genre, Star Wars quickly fails in comparison. The more I look back on Star Wars, the thing that made it great, for me, was the hook of Han Solo and Chewbacca, being these space pirate/cowboys skirting the law living on the fringe. Sounds like Firefly/Serenity....go figure.