Overrated. I hadn't read Sanderson before, but given the number of books he has to his name, I expected much better writing. A lot of the dialog is bad. His attempts at humor are mostly annoying. He jumps from character to character, and is constantly inside the current character's head. There are ample doses of inner monologue.
It's not all bad, though. I respect his ambitious attempt at world building. I think this would redeem the book entirely except that I don't think he quite sold it. There are too many little notes of discord for the world to really hold together and feel like a real place. The dialog was a major barrier here.
I did find his treatment of religion interesting, although it falls short of any real poignancy mainly because it has no continuity with our world. Should my sympathies lie with Vorinism or with Jasnah's atheism? I don't know. (I also couldn't stop thinking of Gene Wolfe's Vironism in The Book of the Long Sun, a comparison that is not favorable to Sanderson.)
I did find the characters mostly likable, despite being constantly in their heads. And the last 100 pages or so really kicks it up a notch. The book is very slow-paced, which would be fine if it were better written. But once things start happening quickly, I found it easier to overlook the flaws. I'm on the fence about whether to continue the series.