Immediately upon finishing Bands Of Mourning, I went to Amazon and purchased this novella. Now, everyone will warn you that you can’t read this book without having read the entirety of the first Mistborn trilogy, and I am no different. But I will further recommend that you read this soon after reading those books, because if your memory holds primarily to impressions as opposed to details as mine does, a lot of the relevance may be lost for you.
There isn’t much to say about the book itself except that it is not at all accessible if you haven’t read the trilogy. In fact, it’s a rather disjointed work, because it fits around the narrative of the trilogy instead of working at all as a standalone. That said, if you enjoy Brandon Sanderson’s work, and if you enjoy indulging in the occasional ugly cry (dat ending yo,) you will enjoy this secret history.