"Inception".

Imagine someone gave Nicolas Roeg two hundred million dollars to make an action movie and you’ve got a sense of what you’re in for.
And for Christ’s sakes, will everyone stop complaining about how complicated the plot is.  The plot is relativity straight forward.  It’s just the dream states that create the dislocation.  (Which I’m guessing was all part of Nolan’s strategy.)
Wait…Let me try this again.
What Nolan has done is taken what is a heart a story about loss and guilt and gussied it up with tropes from action and heist movies and then, in the Pablo Picasso sense of the word, cubed it.
And the damnest thing is that instead of overwhelming the love story, the action and heist stuff amp up the stakes and gets us involved even deeper.
Andre Gregory said in “My Dinner with Andre”(And I’m wildly paraphrasing because it’s been ages since I’ve seen it and I couldn’t find the quote on the IMDB.) that people need experiences that remind them that they’re alive, like going to the top of Mt. Everest.  But since everyone can’t go to Everest, you have to use art to create that experience.
What Christopher Nolan has done used the action movie to take us to Mt Everest and remind us what guilt and loss feels like.
Oh, and for the record.  My feelings about the ending?

SPOILER ALERT

Listen for the slight sound of a scratch as the shot goes to black.

END SPOILERS.

Go.  See.  You’ll be glad you did.