Well, Stj, as for everything but your last point, we've both had our piece, and I agree, I think it does come down to a matter of taste, and we'll have to agree to disagree. I am not someone who blindly follows all movie illogic just because I think the action is cool (I despise Fight Club and Usual Suspects, for example, and never seem to be able to convince anyone that these movies make no sense. It's absolutely frustrating.) But, for whatever reason, all intellectualizing aside, I just loved this movie. It worked on me. Emotionally. The way a Philip K. Dick novel (often a badly constructed and ill-thought-out one) does. I see your points, though, and all I can say is, "None of that mattered to me, because I loved it." Maybe that makes me a bad movie critic. Or a good one. I'm not sure.
As for your last point, though, this one I stand by, and I believe you're objectively wrong. The statement I believe the movie is making may be pernicious, and it may be nonsense, but I believe it to be arguable. I would argue, in fact, that most people, perhaps including even you and I, are not perceiving the "objective" reality as much as we think we are (if such a thing even exists), and that we are, rather, living in worlds of our own creation. I'm not talking about whether the world is round or flat, or whether pigs fly, but about all the stuff that's more vague, more subjective, having to do with perceptions and values and emotions and opinions - I think most of us tell ourselves (unknowingly) what we need to tell ourselves to be sane, and never do we test that world against any kind of objective reality. That is what I found myself thinking about the last scene of the movie, and again, that's why I find the ambiguity both present and interesting.