I think the biggest problem with the PT is that one, Padme dies earlier then what the OT made it sound like. If it were up to me, i would've had her hide on Alderaan and have her die a short time later and then Bail Organa takes Leia in.
And two, GL didn't take in to consideration that their are new fans that won't be surprised that Vader is Luke's father because he spoiled it in the PT.
However, GL did that due to fan requests asking, "Will we see him in the suit in the movie?"