Most readers would agree that it began with Robin McKinley, and it's been sustained by Shannon Hale's Goose Girl, Kristin Cashore's Graceling (which, for the record, I did not like), and more recently Rae Carson's Girl of Fire and Thorns. There are more - Mette Ivie Harrison, Jessica Day George, Sarah Beth Durst, and some with only two names - though there are degrees to each of them. Graceling, for example, features a less accessible heroine than Girl of Fire and Thorns, though the latter is higher fantasy.
Even within an author's canon, there are degrees (Shannon Hale's Book of a Thousand Days is stronger than Goose Girl, though they're both excellent, and Jessica Day George's titles are more playful with this category than others). The strength of each is not in the magic of their fantasy, but in their characters. Magic becomes a burden as well as a gift. Victory over the enemy - which is often a seductive enemy, harnessing its own brand of magic - comes at the last possible moment. It also comes as a last ditch effort of sacrificial strength.
If this seems like a strange way to define a category, just take a look at the titles I'm talking about. They all do something like this: Unlikely heroine discovers a position or power that seems bigger than her, must learn that her inner strength is greater than the mystical strength of her enemies. It's not cliche; it's good fiction.
Shadow and Bone does this. Shadow and Bone does this better than a lot of other books.
Alina and Mal grew up together as orphans, were conscripted into the army together, and have stayed friends despite their very different positions. Alina is a mapmaker; Mal is a tracker. Alina is weak and awkward; Mal is strong and handsome. They are utterly different, but they are best of friends.
Until Mal is almost killed trying to save Alina in the Shadow Fold, and Alina discovers her own power. It's a power she didn't ask for and does not want, the source of her own weakness and the potential for great strength. It's proof of just how different they are, and it will tear them apart - perhaps forever.
Leigh Bardugo has answered whatever call Robin McKinley and those of her ilk have sounded into the vast reaches of the writer's ether. Shadow and Bone is fantasy at its best, displaying a Russian landscape of magic and legend almost as rich as the characters that move in it. This is a book to loan friends but demand that they return. It's hands down one of the best books of the year. And if you need any more convincing, the cover art is beautiful enough to frame.