My reaction was sheer utter confusion the last time I saw it, which was I think at least three years ago.
I admit it, though, when the 2004 special edition came out, I was 13 and I thought it was a really cool change.
I never understood what Lucas was trying to achieve when replacing Sebastian with Hayden.
I've heard that Lucas wanted the face that was a Jedi, but even then, that face turned to the dark side.
If anything, it makes more sense to keep Sebastian. That face made the sacrifice, killed the Emperor and redeemed himself.