I don't see how it is an example of good story/bad script. That is just bad all the way around. He turns bad in a fraction of a second, he goes from hero to "ah hell, if I am gonna be bad I might as well do it right and slaughter kids, but make the impact less by calling them younglings." That was a horribly dumb part of the story. There was no rational for it, no anything for it, it was nonsensical and pointless. "Go do what must be done" "Yes, master". It is not just the script at fault here. There is nothing badass about killing a bunch of kids. That is the work of a worthless coward, preying on those far weaker than himself, even sicker is preying on those who rely on your for their protection. A much better story would have had Anakin dueling Mace Windu as his first act as a villain. That could have been Palpatine's test of loyalty, rather than killing helpless kids,
"Anakin, in forty seconds three Jedi will come in here to kill me. To make of me just another Sith martyr. Executed without privilege of trial, just because I don't conform to their pathetic Jedi rules! Anakin, you know what must be done, don't you?"
"Yes master."
Door burst open,
"Chancellor Palpatine, you are under arrest! Anakin, get out of the way. Anakin! Anakin? (Anakin slowly turns, and ignites his saber) Whatever he has told you, it has all been lies! He is a Sith Lord! That is their way! Anakin! Don't do this!"
and a brilliant saber battle breaks out on screen, Anakin taking on three Jedi while Palpatine sits behind his desk and watches with glee. He is being beaten and realizes it, finally feeling overwhelmed he truely give into his hatred and anger, in a furry of rage and bursting with force lightning, he cuts down the three Jedi in several rapid strokes of his saber.This scene would also give us the chance to see on screen the real power of the darkside in comparison to the lightside of the force. Something that is talked about in the OT, and seen to an extent with the Emporer's lighting at the end of ROTJ, but seriously underplayed and outright absent in the PT.
As for the Clone Wars beginning in a gladiator arena, that is beyond bad story telling, this is Monty Phython level absurdity. Just try to imagine WWII having begun in the Roman Colosseum. Utterly ridiculous!
Another major failure of the PT that is often cited, is its loss of the black vs. white theme we had from the original. The Empire was absolutely evil, and the Rebels were absolutely good. People like this theme. One reason the Lord of the Rings films were so popular, as unrealistic as it may be, people really like the well defined lines of good vs. evil. This is probably one reason I really liked TPM so much as well, the lines are clearly drawn.
In the PT we have the Jedi, who we always imagined being the good guys turning out to be kind of uptight jerks. We have Obi-Wan who is a bit of a jerk, the nagging and restrictive father figure, who leaves his best friend to die along in agony. And by the time we get to the OT he lies through his nose. And our main hero is saving the day and then accidentally murdering whole villages. An army of Clones is made, who made it? A good guy or a bad guy? Ah, who knows. The Clone Wars are seen as a questionable war. We are not even sure what the separatists are doing that calls for a full scale war against them. There is no black and white in the PT, it is all a bunch of gray. And having Palpatine pull all the strings seemed cool at first, but by the end it got to be a little too much. Here we have one man who single handedly brings the whole galaxy to its knees. Would have liked to have seen him as more of a character who managed to work all things to his advantage, rather than the single omniscient individual calling all the shots and ruling both sides.