I think Vaderisnothayden is pretty spot on. I know Lucas didn't intend for his story to come off that way, but as presented it most certainly did.
What was wrong with the presentation of the PT story?
1) Child Anakin served no purpose and, in fact, inhibited Anakin's character development. If Anakin had been 17-20 years old in episode I, we would most certainly have felt a greater familiarity with him in the alternate episode II. At the start of the actual AOTC, we in the audience needed some time to get used to the adult character Anakin Skywalker - time that could have been used more effectively.
2) Anakin is whiny and cocky in AOTC. "The good man that was your father was destroyed". What good man? Anakin was an utter idiot in AOTC and impossible to root for! I know you don't have to like every character in a given story, but the main character of the movie - hell, the main character of the six-part saga, according to GL - needs. To. Be. Sympathetic. Unless you're a whiny, cocky, insurrect jerk, there's no way you can relate to Anakin Skywalker in AOTC.
3) Realism has its limits. OK, you might tell me, yes Anakin was a jerk who slaughtered an entire Tusken village, but in real life good girls fall for bad boys. And if the SW saga was a 1970's Martin Scorsese film or something like that, then fine. But it's not. This is space opera; in the OT, Lucas understood how space opera works. His good characters were heroic and virtuous, his bad characters were evil through and through. Luke and Leia and Obi-Wan and Yoda and Tarkin and Jabba and the Emperor were either perfectly good or perfectly evil. The only characters with any gray areas were Han in SW, Lando in ESB, and Vader at the end of ESB and throughout Jedi. In AOTC and ROTS (before the turn) Anakin is one of those blasted anti-heroes, distractingly so.
And if realism is so desirable, would not a scene involving Mace Windu preparing a tax return be defensible on the grounds that it's realistic? After all, taxes are a part of real life!
4) Anakin's fall from grace really and truly begins halfway through the third movie? Is this really enough time to be plausible? Anakin's pure goodness should peak sometime in the middle of the second movie - and it would have gone that way had Anakin been an adult in episode I.
5) Anakin is going to turn to the dark side because of nightmares? How about in episode II Padme obtains some kind of terminal condition that Palpatine says can only be fixed through Sith techniques? See, in that way Palpatine dangles a real carrot in front of Anakin to fix a real problem.
See, I didn't propose any radical changes here. These suggestions didn't require any new characters or locales. There are other problems that need to be addressed - for instance, I should care that the Jedi are slaughtered in ROTS, but I didn't - but this little list is just a way to repair the problems in the Prequel Trilogy's "A" story.