What is most striking about The Night Circus is not the beautifully written prose, the creative plot, or the well-rounded characters, but the careful interweaving of all these parts and finding the perfect setting to put it all in. After all, the title of the book is The Night Circus, not something more directly about the main characters or the plot or themes or other more traditional routes. And “the night circus” isn’t even the name of the circus itself. It is a moniker, describing the circus more than anything else. Because we are entering the night circus as soon as we peel back the front cover, pushing aside the black, white, grey, and red to reveal the stark black and white of the text - just like the circus itself. 
Although, ostensibly, this is a book about Celia and Marcus and their duel (and eventual romance), really this is a book about dreaming and reading. Although there is love in it, it is not about love. Although there is mystery, it is not about a mystery. Although there is magic, it is not about fantasy. It is all of these things and none of these things. If you are looking for a book with a straightforward plot, a simple to follow theme and idea, this is not the book for you.
The second person snippets, almost like invocations, show the true depth and mystery of this novel. The parts of the novel are being revealed to us just like a circus. We are only allowed to see exactly what Morgenstern is allowing us to see. The circus has a backstage and this novel has one too, one we will never see. Throughout the book, the reader feels like s/he is part of the backstage of the circus (something repeatedly mentioned by the characters), there is a feeling of inclusion. But these second person narratives, although ostensibly meant to make the reader feel more like a part of the circus performers, to pull the reader in even more, really just ends up setting the reader apart even further. The “you” is just another audience member being wowed just as much as the fictional audience members in the book. There is nothing differentiating “you” from “them” from “us.” “You” is never part of “them” (the circus performers). 
Reading other reviews, many people want to force a plot out of this book, to force it to make sense in the traditional narrative sense, but this book is not designed for such mundane and prosaic constrictions. This is a non-traditional narrative model, experimental in many ways, trying to show what a books looks like when it focuses not on characters, not on themes, not on experiences, but on a place and what that place means to the people who come in contact with it. 
Some people might find the slow pace of the novel off-putting or disconcerting, but places move slowly. Places don’t change much. Places, even places that move around as much as a circus, are still fairly slow moving things. Considering that this particular place is frozen in time, it is even more apt to consider that it won’t change much, that nothing will ever move quickly. So this context between Marcus and Celia will never come to some epic duel like Harry Potter and Voldemort, but does the world really need more of that sort of flashy sort of battle? Don’t we have enough of focusing on what happens when pure evil and good enough to look pure good come in contact with each other? Can’t we experience something a little different in this world and not throw a fit? We all have a place that is especially dear to us and we never want that place to change. Maybe it is the bedroom you grew up in. Or your car. Or some natural landmark. Whatever it is, if that place altered drastically you would be devastated. You would feel like some part of your identity was taken away, something that kept this place pure and sacred is destroyed and you can never regain that sense of innocence and peace you found there. This is what this story is trying to capture. To show “you” how this place, this magical wondrous place, is always there, you can always find this magical spot. Any time you open this book, this spot will be here, this place. Any time you open any book, that place will be there, it will be the same, unchanging, comfortable, the same. It will always be pure.