In Cloud Atlas, six stories from six different time periods interweave to make a statement about humanity's connection with its past. One has to admire directors Tom Tykwer (Run Lola Run) and the Wachowski siblings (The Matrix) for attempting so ambitious a film, but I think the movie fails on almost every level.
For starters, each lead actor plays multiple characters across the millennia, and while we can sense the filmmakers' enthusiasm for the stunt they're pulling off, the identity play winds up feeling like a gimmicky novelty: can you spot the celebrities even when they're unrecognizable buried under make-up, or swapping ethnicities and genders? The film repeatedly jumps between the stories to illustrate their parallels and conjunctions, but any greater themes and insights are undercut by the tedium of six expository beginnings, six inciting incidents, six sets of twists and reversals, and six separate climaxes. This would leave even the hardiest viewer in a state of narrative exhaustion, but it's especially unrewarding here because none of the stories seems to contain more than ten minutes' worth of actual substantive content. And it is frustrating and senseless to jump back and forth between endless multiple climaxes, some of them exciting--like the action-oriented escape sequences of the story set in a dystopian future Korea--and some of them markedly less so--like the 1850 story where an American notary is being poisoned by a doctor aboard a ship enroot to San Francisco.
Although I didn't read the novel on which the film is based, I'm sure Cloud Atlas works better as a book than a movie. For one, there's no distracting multiple casting to contend with, and it is also more difficult to adequately develop and intercut six separate plot threads in a movie's two, or even three-hour runtime than in the hundreds of pages in a book. The story of Cloud Atlas itself centers so much on the importance of the written word, with letters, sheet music, articles, reports, and journalism providing continuity across the ages, that engaging with all of these documents on an actual page instead of on a movie screen, would be much more appropriate.
In the end, the film doesn't add up to more than the sum of its parts. It’s an impressive failure, but a failure nonetheless.