For a long time I didn't know how I felt about the IM3 twist but I eventually came to the conclusion that I hated it. I think what took me so long to get my feelings in order is the fact that Kingsley was just so good in both personas, but when you get right down to it we were essentially cheated out of Iron Man's arch-nemesis. Cap got to fight Red Skull. Thor got to tango with Loki. Iron Man got...Trevor Slattery. Actually, no. What really bothered me wasn't so much that Trevor wasn't Mandarin, but that Killian was. He was so damn boring that I literally only remember one thing about him now, and it's my most hated line in the movie:
I WAS THE MANDARIN ALL ALONG!
Yeah, just twist the knife, why don't you. I know that the bluray short implied that there is still a real Mandarin out there, but I have serious doubts that they're actually going to use him in a movie.