The biggest gripe for me with the character comes when:
You side with Orpheus and the Emperor straight up joins the Netherbrain... a being that he has been fighting against all this time. He quite literally goes and enslaves himself willingly just because you do something he doesnt want you to. I knew the guy was manipulative but this was deal breaker for me and made no sense at all.
I can take or leave his character otherwise. Safe to say that I now skip through all his cutscenes after my first playthrough however.
Oh and dont get me started on the Guardian.