One thing that surprised me about the prequels was how bad Ian McDiarmid performance was in in AOTC. I remember the first time I saw him in that I was like, that's it, what happened to the snaky performance he had in TPM? So much character of him in that movie compared to AOTC. He just seemed to be standing around stiff saying a few lines. In ROTS he was better, but still was missing something.

I don't care what people say about Liam Neison, I thought he did a great job in the TPM and comes off as one of the few people to pull off a believable and convincing performance in the prequels.