The dust jacket blurb is awful:
Wool introduced the silo and its inhabitants. Shift told the story of their making. Dust will chronicle their undoing. Welcome to the underground.
The book, however, is great. There were a number of parts in the book where I just hated to keep reading. All of them were parts of people being assholes to other people. There's looking out for your own needs, and then there's just plain greed. The former I understand, the latter I do not. The deliberate claiming of another person as property I also cannot stand.
Upside to this book, it has as close to a happy ending as you can get in a book with the previous two books Wool and Shift prior in the series. The plot in this world doesn't jump between centuries, making it easier to read. It wraps the saga up nicely, lots of small mysteries solved, which was nice.
I recommend reading this book (after the previous two, of course, it'll make no sense without those two first).