I'm... a little on the fence about this one. People warned me that this wasn't very good compared to Gone, but I didn't really consider it for a second. I've read more of Grant's stuff than just Gone - I've also read Eve and Adam, Animorphs, and I'm working on Remnants. (For comparison, most Gone fans have never heard of Remnants and think that K.A. Applegate wrote Animorphs alone.) He's never disappointed me yet. But while this wasn't a bad book, it wasn't quite on-par with what I'm used to from him.
I think the problem is that he spent too much time and energy trying to make the nanobots cool. And make no mistake, theywere cool, but not cool enough to carry a novel. There was a lot of information to give about them, and while he never quite infodumps, the novel is still slowed as a result. The plot took a surprisingly long time to get off its feet, and a couple times, tense scenes were interrupted by necessary exposition. I get that Grant was trying to make the nanobots interesting and realistic, but it would've worked better if he had made things a little simpler.
That said, once the plot got off its feet, it really worked for me. The action sequences where tense, exciting, and unique. Since people with biots control their own bodies and their biots at the same time, Grant often had to write two action sequences at once, yet he pulled it off without a single bit of confusion. The body horror was just as intense as usual, and everything was very unpredictable. My only problem was the cliffhanger. I don't think cliffhangers are inherently bad, as some people do, but this one sacrificed resolution of the plot, meaning that I felt less like I was in suspense and more like I was missing the last twenty pages of the book. But other than that, everything worked for me, just as much as usual.
Alas, Grant stumbles a bit again in the characters. This novel reads older than most of what he writes - Noah and Sadie are both in their late teens, and most of the side cast are in their twenties. Perhaps this forage out of his comfort zone is why the characters aren't as interesting as they are in most of Grant's novels. Sure, they're mostly well-rendered, and Noah and Sadie have a really sweet romance, but that's it. The large cast of side characters are mostly wasted, their potential ruined by the fact that Grant is too busy expositioning about nanobots to write an honest, human moment. They felt like real people, but they weren't interesting enough to carry the novel the way I would've hoped.
But what did work for me was the prose. As usual, Grant's writing is clear, concise, efficient, and effortless. Never was I aware of his presence while reading the book, because nothing awkward ever happened. My one problem was that he insisted on telling us everything about a character's personality the first time we met him or her, rather than him showing it. Other than that, it was perfect.
But overall, I have mixed feelings. I'll still recommend this book, because it's Michael Grant. And I'll read the sequel, because it's Michael Grant. But as (I think it's safe to call myself this) one of his biggest fans, this is not his best work. I'd strongly recommendGone, Animorphs, Remnants, or even Eve and Adam over this - Grant has written far better novels that deserve attention more than this one.