Another fine addition to the Mistborn universe.
Good characters and lots (and lots) of action. The world building is mostly set already from the prior Mistborn books, though it takes it in a new direction and hints at things to come. [a:Brandon Sanderson|38550|Brandon Sanderson|http://photo.goodreads.com/authors/1201547425p2/38550.jpg] is planning 2 additional trilogies in the Mistborn universe and this novel feels like a stepping stone between the first and second trilogy.
You won't get the deep sense of satisfaction from the original trilogy: there isn't a lot of new world building, the list of characters is small and only a few develop meaningfully, and the plot, while fast-paced, ends with a few things unfinished. It left me wondering if the next trilogy will be set a few years from this event or will be decades later and incorporate what the 'bad guys' were trying to accomplish. I'm hoping for the later.

If you care about the world building and the greater scope, the Ars Arcanum (the appendix) is for you. I felt it was great with descriptions of all allomantic and ferruchemic powers (with the exception of 1!) as well as an interesting commentary on the three powers and a mention of the Cosmere.

I recommend this book to any fan of the Mistborn series. If you haven't read any of the books, I'd recommending starting with the first: [b:Mistborn: The Final Empire|68428|Mistborn The Final Empire (Mistborn, #1)|Brandon Sanderson|http://photo.goodreads.com/books/1312038619s/68428.jpg|66322], which is actually well-contained in a single novel despite being a trilogy.