I do understand the better reviews on this book: It's quite an okay YA book and enjoyable for some, but personally I like to be a little more challenged with a book than this. 
 I find it funny that people praise it for its steampunk genre. I mean, I really love steampunk and I am a big fan of the genre but I didn't even know about this fact until after I read the book and some reviews. Really? Steampunk? Just because the cover has some gears on it (not this one, the blueish green one that's newer), doesn't mean this is steampunk. I mean yes, they are in a middle-aged setting with "advanced" technology, but this technology could be seen as magic just as well. So for someone who really likes the genre and explores it quite often, this had nothing to do with steampunk. 
 The story is quite simple, the characters quite generic, the events quite foreseeable. It doesn't offer any surprises or twists that would have made it a little more interesting. It implies just too much from page one to leave anything in the open. Oh the protagonist has weird dreams and seizures about the outside world? And the princess knows just a guy that someday mysteriously disappeared that's also from royal descend? Could it be? I mean, it would have been really interesting if Catherine Fischer surprisingly went "Oops, there's another boy you don't know about, I only lead you on! Joke's on you!" That would have been interesting. But no, the mysterious boy of course is the leader chosen by fate that's also the missing prince. Shocking. 
 The settings in which the story takes place feel rushed and incomplete, as if they only serve the purpose to fill in blank space during the heroe's journey. Personally I found that very disappointing, since the idea of this giant prison no one even really knows about that has a life on it's own seemed really interesting, but we're left with mere short descriptions of the world inside and that's about it. There are weird rooms and people and creatures but no one really knows why and no one cares to find out. 
 Catherine Fisher's writing style seemed, although not bad, rather simple to me and often left me bored. To be honest, I only finished the book because it was quite short. It just seems like another YA novel that tries to mix up every literary concept that's worked in the past few years to create the ultimate novel, but fails by mixing up way too much to keep it interesting or organized. It doesn't really fit a genre and apart from the prison idea it doesn't stand out in any way. 
 I'm sorry to disappoint, but I'm disappointed. 
 Thanks for reading. 
 Ps.: As always, sorry for my english, I am a non native english speaker so there may be some mistakes in my texts. I'm still learning. Thanks!