There's a line in 'Midnight in Paris' that Hemingway says to Zelda Fitzgerald about her short story, something like 'there was some fine writing in it, but it was unfulfilled', and that's how I felt about this book. Stylistically, it was really quite good; the prose was neither overwrought nor so simple as to be sophomoric. On the other hand, the book's actual development was a huge disappointment. Levithan builds his world carefully, establishing clear rules for A's situation--every day s/he wakes up in a new body, spends the day there, and then repeats the process--albeit never with the same body twice--on and on, into eternity. Obviously, this is a pretty tough position, and it gets worse when A inhabits some douchebag's body and falls in love with the guy's girlfriend. The rest of the book is concerned with A's efforts to spend time with this girl, Rhiannon, even to the detriment of the lives A is borrowing. A skips school, misses appointments, bewilders family and friends, and convinces one previous inhabitant that A is the devil, going around possessin' everybody for nefarious purposes.
That secondary plotline had huge potential for interest, especially since it necessarily revealed more about what A was and why their life is like this. Unfortunately, the reveal a reader might hope for is not so much an illumination as it is a fast-fading spark. Ultimately, we learn nothing concrete about A's circumstances (except that similar beings exist), and there is also nothing A can do to change them. I expect that Levithan was going for a solemn meditation on the nature of love & the kinds of sacrifices you have to endure in order to make it work, and for most of the book I was pretty much buying it. The ball drops in the last 40 pages or so, though, and the conclusion just is not satisfying, at least not for me.
One point sort of in its favor--A inhabits all different kinds of bodies, of all different racial and gender makeups, including a few gay and transgender teens. Levithan's hook enables him to cover the broad spectrum of identity, and he definitely does. Unfortunately, none of these characters are given much depth, so at times it felt like Levithan was just ticking things off of a checklist.