So, if there's no magic sword, then why is there a chick with rainbow hair practically hugging one on the cover? It's a metaphor. Fantasy artists love those. The short, short, short version of the plot is that there are two countries (Halladren and Idria) and everyone in both countries is pretty darn sure they're about to have a war. Excitement follows.
It's a simple premise, but relatively unique. Generally the war is well on its way in any novel and it's never the case that people are trying to stop it, mostly they're just trying to win. It gives the book depth because the good guys and bad guys don't wear certain badges, colors etc. and don't necessarily all hail from the same place.
Sanderson loses points by making the Church into the villain (let's just say that's been done before), but wins big by allowing for shades of grey in his main characters. His heroes are unlikely, but as previously mention they have depth, and his extras are equally three dimensional. There's a princess who isn't, a King who isn't, and there are spies who turn out to be more... or less... depending on how you look at it.
Politics aside, what makes this good fantasy? First off it has a unique approach to magic. Everybody has BioChromatic Breath, which can affect the world around you. The more Breath you have the stronger you are, and people will sell their Breath. Or you can off them and take it. You can tell how much Breath a person, or an object, has by how colorful it is The amount of magic you carry affects the way you look, and how you sense the world. In addition to the Breath, there are "Gods" that walk among them who have died, are reborn, and can use their new life to change the world- if they are willing to die again.
For those of you that are hopeless English geeks, you can reflect on this and chortle. That's right, the man inserted an actual deus ex machina into his own plot. The depth of that irony is the number one reason why I christened Bad Fantasy Rx with Warbreaker. If ever there was a genre that abused the deus it is fantasy, and Sanderson's nod to that is done so cleverly it is easily overlooked.
So far we've got good magic, deep characters, and interesting plot twists. Sanderson has a solid story, but the icing on the cake is that he writes exceptional prose. His books tend to be upwards of 500 pages, but are they draw you in and keep you reading.
PP, 3-11, 33-44,46,152-157,374-380,498,512-516,526-527,600-602,629,635,650-651