First, if you haven't read Sanderson before, this would be a very spoiler-y start to the Mistborn series. I enjoyed reading from the beginning, and I think you would too. At least go back to book 5 though.

Second, if you liked the original Mistborn series, I think you'll like this book. Previously shallow characters (or even just some of their traits) were filled out quite a bit. I found myself enjoying some of the characters even more than before, so that was good.

Finally, the book isn't as long as some of Sanderson's other writings. But the story didn't feel rushed and I feel like this is an excellent addition to the Mistborn series.