I'm convinced there's not a single moment of non-dream in the entire film. It doesn't matter whether the spinning totem falls or not after the cut-to-black at the end of the film; it's shown falling a couple of other times in what I believe are dream sequences.

Most of the "real world" stuff has the same crazy physical logic of the dreams. And at least one important plot point only makes sense if everything's a dream, i.e., why Cobb can't see his kids - which is his entire motivation and drives him to extremes. I note it doesn't drive him to buy two tickets for them to come to Paris, which would be perfectly reasonable in the real world if this was his real problem. It's only in dreams that obstacles have only one solution that makes no real sense.

Anyway, I prefer that interpretation to giant, gaping plot hole in a film that took 10 years to make. So I'm sticking with it.