For me, Episode III was the only prequel to have any emotional engagement. On the first viewing, I was pretty moved. I actually felt for Vader as he appeared in the OT.

But on later viewings, when the emotions didn't hit me as hard, I began to see the faults (stupid droids, no Sifo Dias resolution, Sidious's goofiness, Anakin's reason for turning, etc)

I think Padme was the real wasted character. She went from almost being the main character in Episode I to being a pretty incubator in Episode III.