Okay, just finished it. I really liked the first half or so, maybe the first two-thirds. I liked the writing style and the narrative voice. The ideas were fresh and interesting. I was ready to write a "SO cool!" review. 
 But the J thread (I won't post details so I don't spoil) seemed to be pushing things; and as that subplot evolved (or, er, got stuck), I felt like the metaphors got a bit heavy-handed, too. What at first seemed charming and thought-provoking by the end seemed a little sledgehammered into the prose, as if the narrative threads were better off concluded hurriedly with unanswered musings rather than followed to their ends at the same pace at which they began. 
 That said, I still liked the book overall and would recommend it.