Amazingly innovative, Cloud Atlas is a book that’s hard to describe and even harder to put down. I didn’t like it, but I absolutely think you should read it because it’s that interesting.
The (presumably rather Westernized) Buddhist themes of reincarnation and interconnectedness didn’t really bother me, though I prefer their opposites, transience and individuality. I think the movie scores better on individuality: there’s maybe as much emphasis on the line, “What is any ocean but a multitude of drops?” as there is on “Our lives are not our own; we are bound to others, past and present.” In both the book and the movie, the nature of truth is a major theme, and one I like.
In the book (but not the movie), two of the six protagonists were rather despicable, and the book’s view of humanity is bleak: the message seems to be that we keep repeating the same mistakes and don’t deserve a civilization, since we keep wrecking it in various ways, heroes notwithstanding.
For a kind of overview and more on what I thought including SPOILERS, keep reading, but only if you’ve read the book or don’t intend to.
Also see my post on the movie Cloud Atlas (2012).