0
Yoda's an M. Night-head, so I can see how he'd have high expectations for a twist.
What matters is how consistent the film's twist is with the subject matter and what it says in relation to that subject matter. It's not just a film about Teddy but the state of mental health practices at the time. If you go back and watch the film again, the "role play" aspect really becomes clear. You get to see not only how Teddy reacts but how the entire island is trying to help him realize something. It really is just one huge therapy session, and the whole detective film with WWII flashback shtick is merely a projection of his pathological paranoia. In this way, I think one can argue how much film shapes our perception of reality. It is not just that Teddy was reliving his life, but rather, it was how he relived it in a way consistent with certain genre tropes, as if emulating the reality of film in order to make up for the deficit in his own life, having erased a good portion of that life.