The book is a series of nested stories, spanning over time and space. I don't want to say too much about it, because most of the pleasure of the text is in the discovery, but basically, they stories are all sort of connected, but the author can't seem to settle on what kind of connection that really is. Meanwhile, the stories themselves are all fairly interesting, a bit o' the old excitement. Mitchell is to be commended for writing in so many different voices, most of which are quite successful and compelling.
Reviewers on goodreads.com are crazy about it, praising its cleverness and saying it's really a life-changing sort of book. Well, I disagree. It didn't seem all that brilliant or profound to me, just sort of interesting. For a 500 page book, it certainly goes quickly, and like I said, it's a pleasant read, but the thing is, it just didn't seem all that profound, nor did it really have much to say in terms of broader reflections on humanity, society, etc. Or so it seemed to me.
So as mentioned above, the overall effect was similar to the Perlman novel, to me, though Cloud Atlas at least was less ostentatious about its own supposed cleverness. Ultimately, I don't particularly recommend either book, but they're not altogether terrible either.