I almost couldn't finish this. Don't get me wrong, the concept is great, and the 'other London' more richly imagined that anything I'd expected. This is excellent world-building; the imagery bursts forth from every page. However, the characters just didn't do it for me. Deeba gets more and more annoying as the story progresses - and speaking of the story: It. Just. Wouldn't. End. On and on it rambled, until I found myself not even caring about the outcome.
I'm sure that younger readers, for whom this was written, after all, won't mind, but I found the last quarter painful to read. I think I might try one of Mr Mievielle's adult novels next!