I'm not certain what I think about the novel, but a few things should be pointed out. There were clever aspects and the writing was clear and obviously aimed at kids. The debt to Gaiman was obvious, but so was the debt to Michael Ende. The word-play drove the narrative, but more importantly, it drove the plot. In some ways, it was clever and interesting, but I was left wanting something else. I couldn't believe how much the novel was about umbrellas, unbrellas, and rebrellas. I suppose my main complaint was with the wrap up of the smog. Yes, yes, clever and all, but then again, not so clever. After sitting on it and letting it digest in my head, it just felt cheap. 
 That's not to say the book it not worthwhile, because it is. It was very cute and follows a very long tradition of YA novels that bring the little awkward girls into full blown heroines. I've read much much much worse YA novels, so I suppose my harshness is there in direct response to how much I did enjoy the beginning and middle parts and sat wondering how a resolution would come that didn't seem ultimately contrived. 
 In all, I did enjoy it, but I know I could have enjoyed it much more.