Exactly. The totem is "an elegant solution for keeping track of reality." And reality is the garden on the cliff, something emphasized not only by the comparison of life to a dream and dreamers to "figments" and "shades", but much more directly in such lines as Cobb's father urging his son to "come back to reality" when none of the characters are even dreaming.

We know Cobb doesn't need his totem by the end, because his rejection of Mal at the climax is an expression of faith. To understand the implicit alternative, look to the parallel heist sequence which opens the film. There we had a very different Cobb place his faith in the "reality" of Mal when he lowered himself out the window above a fatal fall. Nolan emphasizes that this is the wrong decision by showing us Cobb's immediate (biblical) fall, blasphemy and then betrayal and loss. Death destroys the world by water as foreshadowed in the parable that opens the film.

At the end of the film the logic of this sequence reverses. Cobb resists Mal's temptation to stay with her in limbo. He rejects her for the first time ever, telling Mal she is not "real" where even moments before he was expressing lingering doubts to Ariadne ("how can you know"). And whereas his lack of faith had previously led to his defeat, here his expression of it leads directly to Fischer's symbolic reconciliation with his father. And while the film presents another death sequence as required by Matthew 7.24, this is but prelude to a heaven sequence that breaks the endlessly circular logic of the dream world / penrose staircase. The rules are violated because they no longer apply: Cobb is free of the maze.

Your explanation has just made the movie more interesting to me. Until now I thought it was quite idiotic, but your revelations do make sense.

Though I still think that the ending scene is badly handled. If the point is that Cobb doesn't care any more about the outcome of the spinning top, then Nolan should have just slided from the image of the top to Cobb and his children.

By zooming in on the top and cutting the shot right before it should falls, it just adds this unneeded baggage of questioning whether all that happened is real or not. Like some sort of magic trick. "Do you doubt what you've just seen?" And I just didn't find that that was the point of the movie.

I think that's a really good comparison, because it really is a magic trick, isn't it? I think most good heist films are in the sense that the pleasure is in the misdirection: what makes them satisfying to watch is being "in on the game" -- seeing all of the clues arranged in plain sight and watching how the director pulls it off.

So Inception might not be for everyone since it's heavy on narrative and light on character development (we don't see why Cobb changes, he just does), but there's all of this wonderfully meta sleight-of-hand just below the surface as Nolan tells us how he is making the film. Even beyond the symbolism, the very rules he outlines for how to create dreams apply equally well to the film itself (make the plot a paradoxical maze, get the audience lost in it while you plant ideas in their heads, and make the message stick by forming it around a core message of positive emotional catharsis). And yet we are still surprised, or I was at least!

Anyway, hopefully if you see it again you'll like it better next time. I personally think it's hands-down one of the best films in the last decade, and it's a real pity it got shunted off at the Oscars when it should have swept the field.