An interesting and pretty original idea. Since it's a story, it moves quite rapidly through Benjamin's life, but you get the point. It reminded me of Eliade's novella, Youth without youth
, except in that one the old man gets younger right away, struck by lightening.
Too bad the movie sucks. I successfully wasted almost 3 hours of my life to see a brilliant idea transformed into a cheap love story that has (almost) nothing to do with Fitzgerald's original story.