I haven't read the book. I would like to read the book, and I think I even intend to, now. But this review is based on not having read the book. All the same, it sounds like what bugs me about this film is an artifact of the film, not the book.
Stop. Go read David Edelstein and Kathryn Schulz's taidan on the film. I agree with most of it.
Okay, here's where I disagree. I had a lot more fun with the movie than it sounds like Edelstein did. In fact, I only got disgusted with it in the last ten minutes or so. Up to that point I had a great time watching Tom Hanks and Halle Berry have a great time playing goofy genre roles, and also trying to figure out how all the pieces fit together. So I recommend seeing the movie: you won't be bored, and there's a lot of wonder in there to savor.
That said, when all the pieces do fit together, you realize that they don't fit together well. And the overall picture they're creating is much less impressive than the various pieces were promising it would be. Like, you get to Sonmi's final speech and you're thinking, that's it? That's all they're trying to say? Pfft.
So, dig. This movie is positing reincarnation of a sort (with a birthmark identifier that's, um, imported from Mishima). And it's preaching some kind of what-goes-around-comes-around morality at the end. If you've taken Asian Religions 101 this puts you in mind of Buddhism, samsara, and karma.
The problem is, the filmmakers seem to have skipped most of the lectures in Asian Religions 101 and forgotten to do the reading, because they don't seem to have worked out the karmic cause-and-effect relationships between the various incarnations. Like, it's fun and instructive and thought-provoking to see Tom Hanks doing this thing in the one storyline and this other thing in the other storyline, and see the birthmark pop up on this person here and that person there, but I don't see any consistent application of karmic logic behind why Tom Hanks (or the reincarnating soul that Tom Hanks represents?) has it good in this incarnation and bad in that one, or why the comet-birthmarked One (yes) is in this situation here and that situation there.
Folks, Buddhism works because of karma. You take samsara as a given, then bring in karma to explain how it all fits together, and finally bring in dharma to explain how to cure your karma and escape your samsara. Take out karma and the dharma makes no sense.
Without that kind of rigorous working-out of karmic cause and effect, Sonmi's final speech adds up to little more than, "Be nice to each other. Because it's better that way."
Which isn't to say that the eternal recurrence implications of the body-switching don't have their resonances. I'm just not sure they're the intended resonances. Watching Hugo Weaving always end up as the heavy, watching pair of lovers after pair of lovers and master-slave relationship after master-slave relationship, you come away feeling that human beings are doomed to always interact with each other according to a few basic archetypal relationships. And maybe we are - but "Be nice to each other. Because it's better that way" isn't really going to get us out of that.
So maybe that is all they intended to say with this film. We're all doomed to be lovers, or masters and slaves, or exploiters and exploited, and the only real way out is to just try to be nicer to each other. I certainly can't argue with that as a piece of truth. But in that case, why do we need the reincarnation business? Why do we need the madly fractured puzzle structure for the narratives? I mean, Planet of the Apes did all that with one scene at the end.
So what I think we're left with here is either a film that's about reincarnation and karma but gets it wrong, or a film that's not about karma that just throws reincarnation in there to fuck with our heads. Either way, it's a film that gets less satisfying the more you think about it.
And, okay, let's talk about the yellowface. I actually liked the idea of having the main actors and actresses show up in different "bodies" in the different stories - switching races and genders. If you're going to talk about reincarnation, this is a pretty good way to do it. But it's pretty clear that the filmmakers lacked the courage of their convictions. And that's a good thing: one wishes they'd been a little more cowardly and scrapped the whole idea, because in practice it's lousy. I mean, you can have Halle Berry play in whiteface and yellowface and maleface, but you can't have anybody playing in blackface - because blackface is offensive. But actually yellowface is offensive too! Letting Bae Doona play one scene in whiteface doesn't make up for having Sturgess play a sixth of the movie in yellowface, bro.