Oathbringer is the third volume in the Stormlight Archive featuring strong themes, great character development, and ramifications for Brandon's world at large-the cosmere.
... a conglomeration of exquisite world-building, unpredictable characters and sweet, sweet magic.
Word of Radiance, impossible as it seems, has managed to surpass the dizzying heights of Way of Kings. The characters are better developed, and the magic system is gradually melding with the plot.
The build-up is just as lengthy as in Way of Kings, but the climax is far more intense. There are numerous plot twists, not at the middle, but at the very end of the book.
The plot deals with a great number of themes: betrayals, hate, morality, and honor. The plot is incredibly complex, relying heavily on the multiple blurred protagonists and villains and a lot of myth and lore.
The characters, despite their awesomeness, are greatly flawed. This is not a good vs evil book. The actions of the supposed protagonists lie somewhere between perceived good, and outright selfishness. This means the characters aren't particularly G.R.R Martin-grey. They're judged based on their perceptions of their own deeds. It makes for a seemingly character-driven plot line.
The best part of the book is the magic. Quite simply, this is the best book of magic I've ever read. I can say confidently that the magic system of Stormlight Archive is the best I've ever seen in Fantasy Fiction. And it's only going to get better!