JFTR, I’m not just referring to McDiarmid in TESB; I’m referring to him in ROTJ, too. Honestly, I detest Palpatine in ROTJ; he’s 1-dimensional, unsubtle, and he’s incapable of making a good argument for why anyone should turn to the dark side. He’s a live-action version of a Saturday morning cartoon supervillain – an incompetent cornball who sits around his secret lair cackling to his underlings – a far cry from the low-key Palpatine Revill played.
Of course, I don’t pin the blame on McDiarmid himself; he’s a good actor, and as even the PT’s shown, he’s capable of conveying subtlety. I blame the shoddy writing and direction of ROTJ.
I never liked the Emperor. I still don’t. I disliked the fake, put-upon voice. It just sounded like he was trying too hard to be/sound evil. I don’t know whether this was an acting choice or the direction he was given, but I think it was a mistake.
Unbelievably he was even more over-the-top in the prequels.