Some of these books of David Mitchell are odd and some of them feel almost epic, while still others are just shocking by how much strong voice coming through the page, and some have it all. This is one of those books, the closest novel to Cloud Atlas out of all the books of his that I've read. 
 It shares the same basic concept of loosely-tied novellas with strange immortal creatures either living their lives among the humans or actively engaging in a far-ranging and explosive war with others a bit like them, but one thing is certain, they're firmly ensconced in broad stretches of time, even if they're able to hop through history. I love the SF features of these books perhaps more than most who read Mitchell's books, because it's my primary fascination. 
 However, taken in context with everything else that's going on for the majority of the novel, it can appear rather strange. For one, we're constantly and deeply immersed in the lives of the main characters, and whether or not we're a young girl who hears things or a famous author having a wild time amongst his peers, breaking conventions and fourth-walls, we're often so deep in the setting and these minds that when the SF stuff comes around, it's rather a shock. 
 Well, to me, it's rather fun, but these are the things that tie all these wildly different novellas together even more than common themes such as counting time. We all live in bone clocks, after all, experiencing birth and growing old, and it's kind of a fun feeling to experience it outside the loop both as a reader and as another character, too. 
 I am undeniably impressed by the writing chops and the overall sense of structure, the crystal clear voices, and the huge array of techniques, but to be honest, it often feels either too-understated with the ideas it's trying to push across the page or they're lost in the wide world of admittedly interesting scenes and events. 
 For example, before the slow but interesting fall of civilization in our near future, we had a what might have been a pretty cool and exciting end to the whole novel, but while the structure is undoubtably done for some purpose that eludes me at the moment, I'm left with the feeling that I'd have liked the novel better with just a slight rearrangement. You know, a bang at the end instead of a long decline after the bang. 
 I'm often reading this novel while scratching my head, marvelling at the mastery and wondering if I'm missing something. Sure, I can bring my brain to the table and construct something appropriately deconstructionist to match the craziness in the earlier novella, but is that even appropriate outside of that novella? There's a lot of different writing styles in play, and I assume the author is attempting to lead us through dimensional doors with different cultures and outlooks, so why would he force us to a DFW dance while we're blowing up our enemies with psi-bombs? No Comprende. 
 On the other hand, if I'm just meant to go along for the ride and piece together whatever I want out of it, then I guess the novel is doing it's job admirably, but Mitchell writing somewhat schizophrenically and I kinda wonder if he ought to choose between the amorphous readings or the strict ones. There's such a tight voice in each, I kept looking carefully for the strict, from connection to connection, but it was really frustrating unless I just let my eyes un-focus. You know what I mean? Everything is there and clear if I just let go, but in the meantime, all that effort was kinda wasted. 
 So I got a little frustrated. No big deal. I enjoyed the novel as entertainment, and enjoyed it even more as it gave me more and more huge glimpses and even a grand outline of the entire connected worlds between the rest of his novels. That part was very satisfying, indeed. It's just the satisfaction of this novel by itself that suffered a bit, as if it needed either a grand and merciless editor or the freedom to be two or three times as long as it actually is. (And it's a pretty hefty book already.) :) 
 Very decent and well worth it to Mitchell fans. Not my favorite, but it is kind of necessary for global enjoyment. :)