I don't remember what prevented me from reading Mitchell before, despite having another of his novels (Ghostwritten) on loan for several months. It was the opening, probably; Mitchell seems to begin with voices that I find mildly uninteresting, though I've only tried twice to read him.
What seemed to be a foggy beginning for Cloud Atlas wasn't, it turns out. Ewing is pleasantly reminiscent of Crusoe and Ishmael, and so I agreed to push through what seemed like a smug imitation of nostalgic-albeit-tedious travel narrative classics. The smugness revealed itself to be playfulness; by the time I arrived at the second, wholly unrelated chapter (different time, different voice), I was very ready to enjoy the gimmick of the book's structure. Note that "gimmick," here--given Mitchell's talent--can only be spoken with a tone of admiration; as the subsequent chapters began to neatly reference the previous chapters, I was hooked.
The book, because of its many voices, feels satisfyingly epic. Because of Mitchell's cunning, the book also feels whole, with its various plots interwoven, but not to excess. The connections that exist between chapters range from being wonderfully almost-believable (the half-journal holding up a bed-frame) to forgiveably underdeveloped (the reappearing, inexplicable comet).
What the critics say about Mitchell's ability to seamlessly jump from genre to genre seems spot-on. His imitative abilities are impeccable, due maybe to his frightening attention to "period detail" in word-choice. He also very successfully hides any underlying common voice of his own; I'm curious about what he sounds like when he writes as himself.
In the end, Mitchell avoided the major danger I sort of expected to come about from relying so heavily on elaborate genre-jumping: descending too frequently into a tongue-in-cheek mockery of the various genres being referenced. Cloud Atlas was particularly fun, I think, because Mitchell seems to hold quite a bit of fondness for the sources of his inspiration; he doesn't seem to mock, ever.