Finished Ghostwritten not too long ago, and I have to say Cloud Atlas beats it. I love the way he writes. He's one of those authors where when I'm reading them I get very caught up with their technical skills (the others being Chabon, or Nabokov, or Amis, right the top of my head, I'm sure there are others), simply admiring their ability to write the way they do. Like savouring the words. Hard to explain. Like you want to read the words over and over again. Blah.
I was blown away, frankly, at how 7 distinctly different stories were written in such distinctly different styles and voices, all the same person for Cloud Atlas. Amazing. He gives me this impression of being this precocious kid who submits a 10 page report complete with Latin quotations for a high-school 2 page summary assignment on the Roman empire. The smartass class nerd.
Anyway, at first I thought his effort in Cloud Atlas was very smart, then I read Ghostwritten and found that he simply improved on the art of layering stories on top of one another which he started earlier is his career.