I've read ordinary books in the past year, and a couple of extraordinary books, and this is an extraordinary book, it definitely isn't ordinary. But the funny thing is, a plot summary would make it sound not only ordinary but deeply derivative and imitative.
It is a loving tribute to, primarily, Narnia, but also to any other fantastic place you've ever wished you could go. It is also a meditation on the cost of actually going there. It's also bildungsroman, school story, quest epic, and many other things.
Which is to say, it isn't any of those things but a thing of its own.
Yes, yes, kid gets introduced into a secret school where you learn to be a magician, but any resemblance to Harry Potter stops dead right there. The kids -- young adults: it's a college, not a secondary school -- at this school aren't divided into poncey "houses," they don't have stupid rivalries, and they sleep with each other.
Mainly, it's about real people in a real-seeming place.
And the school part is over less than halfway through the book anyway. What happens after that ... well, I just won't say. But it's good. Really good. And that's enough to say about it.