I enjoyed the progression of Vader from a "whiny teen" to what we saw in the OT. Would it have been better to have Anakin just waiting to turn to Vader? Adds more depth to the character and the OT IMO.
By making Anakin whiny, no one actually cared about his path to becoming Vader. There was no moment where we felt for the characters downfall because we didn't care about the character.
Yeah, there's so many things wrong with the prequels, it's hard to know where to start, and we've been over it so many times before, it's hard to get motivated to start listing them all, but Anakin's characterization is the single worst thing, and even if that had been the only problem, it would have been enough to sink the prequels on its own,
A story starts with the main character and the audience's interest lies in having some sympathy for that character. The guy could be a gangster or a serial killer, but as long as the writer give us some "in" to liking the charatcer in some way, we're along for the ride.
But Lucas gave Anakin no likable qualities at all, or even qualities we could respect. He wasn't smart, he wasn't strong, he wasn't noble, he wasn't even a cool, powerful, villian. He was contemptable, which is far worse than merely being evil.
Contrast him with the Emporer, who everyone seems to like as a character. Why? He's not a weakling, that's why! Lucas picked the one ironclad way to sabotage his main character. After that, there was no salvaging the story.
If you want to see what Lucas ahould have done instead, watch The Clone Wars.