The original Emperor was terrible. Cheesy makeup, bad acting, wooden dialog. They tried to "fix" it by inserting Ian McDiarmid into the DVD versions, but the revised scene was tarnished by one of the most ill-advised exchanges in the entire tri-trilogy:
Emperor: "We have a new enemy. The young rebel who destroyed the Death Star -- I have no doubt this boy is the offspring of Anakin Skywalker."
Vader: "How...is that possible?"
Emperor: "Search your feelings, Lord Vader. You will know it to be true."
WTF!! First off, SPOILER ALERT! Second, there's NO WAY that Vader was THAT DUMB and THAT out-of-tune with the Force. I mean, come on. Everyone knows that his name is LUKE FREAKING SKYWALKER. Vader already made a point of targeting Luke (by name) when they were attacking Hoth. Vader knew exactly who Luke was before talking to the Emperor. And then all of a sudden he tries to play dumb like he's on Maury Povich?? I don't think so.