Not much to say about this one that hasn't already been said, but it's very good. Appealing characters, a unique and well thought out magic system, and Sanderson's typically thorough worldbuilding.
Sanderson isn't the most lyrical of writers, but this isn't the kind of book that needs it. Instead it's got solid pacing (better, in fact, than Way of Kings, this is a lot tighter and always moving forwards), and plenty of action.
I'm not typically a big fan of heavy politics, my deep abiding love for Dune notwithstanding, but the interspersed action and the characters kept me interested through the dull (to me) bits. I suspect that book 2 might be even more political, now that the heroes are inside the machine, but I'm going to read on anyway.