This book sure is hella different from the first David Mitchell that I read, Black Swan Green. But I found it just as absorbing. Cloud Atlas, though, is definitely a more complex book, if only for the unusual structure of the book. There are six stories, each one except for the last, interrupted somewhere in the middle of the narrative. The story is picked up again later on in the book. Each chapter is mirrored in the second half of the book.
Another unusual thing about the book is that when a story is interrupted and another story started, the main character of the proceeding story is seen reading or watching the previous story. Each story is told in a different style or genre. There is apocalyptic sci fi, dystopian sci fi, the typical mainstream thriller, and others. While the stories are connected in some themes, the stories can actually be read separately as novellas. In fact, some stories I responded to much better than the others.
I think it's amazing that Mitchell writes so effectively across genres, and in different, but very believable voices. The book also invites analysis, in trying to find out what themes tie these stories together, and what this book is really about.
I would definitely recommend this book, I loved it, and it strengthens my desire to read even more David Mitchell.