It was OK. And that is bad. I mean, this is Brandon Sanderson we are talking about. "OK" is not good enough.
There were many excellent points in the book. Good action, fantastic worldbuilding.... but the story... didn't finish. Didn't wrap up nor give actual closure. We never got to know Calamity, not really. We don't know why nor how.
The writing was very good, but the storytelling, the plot, was below par. Very unfortunate.
Sorry Mr. Sanderson, maybe you should slow down your writing pace and focus a bit more on your previous quality, instead of quantity. I hear you curse John Scalzi in your Writing Excuses podcasts, but he has one big flaw: bland repetitiveness. And now you are starting to copy that.
Go back to quality, please.