I hate what they did to him: they turned him into a silly clown 😄
If you think about it, even in ROTJ he is kind of silly, like when he does his usual evil laugh, but it was much more subtle: for example, we could hear him laugh, but they never actually showed him laughing on camera like they did in ROTS (except maybe once when Luke cuts off Vader’s hand, but just for a moment).

P.S.: 😄 In the Italian version Palpatine is extra funny because he sounds like Gollum when he says “I’m too weak!” (he’s in fact dubbed by Gollum’s voice actor 😄 )