My problem wasn't how they did, but that it was done at all. To me, he was much more dangerous and scarey when he was a mystery.
Truthfully though, for me, it was just the final nail in the already vastly shrunken universe. I hated that he was switched to Luke's father between films (more writer's block). Showing him, while disappointing, wasn't that big a let down at that point. He was already ruined for me.