Clearly the ending is MEANT to be ambiguous. Anyone who argues that it's NOT meant to offer at least 2 possible interpretations is being disingenuous. Yes, it is objectively strange that the kids are in EXACTLY the same position at the end as they are in his last memory of them. Is it impossible? No, just strange. They're also, I believe, wearing the same clothes. Again, not absolutely impossible, but very strange. Also, their being the same age - strange, and especially strange considering the movie DELIBERATELY avoids mentioning how long Cobb has been in exile. It would have been an obvious thing to put in the script somewhere, and he deliberately leaves it out, so that it's, again, possible that it's real, and still very, very strange. It is disingenuous to think DiCaprio has chosen dreams (or failed to distinguish them from reality) when there is no reason to think there are any kids.
And the spinning top does, objectively, begin to topple for about a millisecond, and then more or less straightens out. And again, this is done to leave both options open. Of COURSE the top doesn't absolutely fall, or absolutely spin forever - the only reason it's effective as a last shot is because it's ambiguous.
It's also brilliant. Reminds me of the end of Philip K. Dick's Ubik, where the guy finds the face of his employee on a coin in his pocket. Anyone who's read the book knows what I'm talking about, and knows that this ending may very well have been inspired by it.
The top does not straighten out again.
The kind of evidence for saying the final sequence is a dream is the same kind of evidence for saying that we never, ever, see reality during the entire movie. The mazelike streets, the nightmarish squeeze, the inanity of corporate gunsels roaming the streets shooting, the sudden appearance of help. True, it breaks the rule that dreamers start in the middle of a dream, but the top falling says that the kids are real too. The problem of course is that if the whole movie is a dream, huge numbers of scenes are pointless.
DiCaprio's problem the whole movie is to get back to his kids. If he gets back to his kids, he wins. The movie ends when we find out the hero wins. The top spinning so long is just a fakeout. When it starts to fall, we know DiCaprio won. We see the same kids in the same clothes and the same positions so we can see DiCaprio finally beholding their faces. A different image could not contrast with the earlier image of failure, when he cannot see their faces when they turn. He's back, taking up where he left off.
The idea that the ending is weakened if this part is unambiguous makes no sense to me. DiCaprio rejects reality and wins. Murphy is fooled by dreams. Does he win, or lose? The contrasting stories provide all the ambiguity anyone could reasonably want, with the added bonus of actually being about an issue we could reasonably care about. How could anyonereally care about the mostly wooden characters lurching through mostly boring action sequences? How does not knowing what happened make it any more interesting?
Incidentally, the explicit announcemnt that Moll had rented (surely no Frenchwoman would let herself be called Mal!) the same suite was probably meant to tip us off that there was indeed more than one room. The U shape was probably just an easy way of making sure that DiCaprio could come out onto the ledge (for suspense as to whether he jumps?), still face Cotillard, but not have any chance of actually physically stopping her. Not one of Nolan's movies have encumbered themselves with realism when a cheap thrill was to be had, so the notion that this time he even thought of a homicide detective finding holes in Cotillard's posthumous story strike me as nonsense.
And, Dave James
above is correct. If Watanabe can figure out from the carpet that he was dreaming, DiCaprio will figure it out. That
realization is the dramatic climax of his arc. Without it, then his arc is unresolved, which would not be good writing, inasmuch as he is the hero. Whether the movie is about dreams (unlikely, and to be hoped not, since it doesn't actually do dreams well, it does virtual reality,) or about movies, dreamers wake up and movies end. The idea that the story can end with DiCaprio lost in dreams (or lost in movies,) ignores this simple fact. The implicit idea dreams or movies can go on forever makes these interpretations facile nonsense.
The movie is not
brilliant, it is original.
That deserves tribute, but not at the expense of spouting nonsense.