In the final novel of the Silo Trilogy, Hugh Howey makes up for the lagging back-story which plagued Shift. The action picks back up where the first two novels end, but this time we see the characters from Silos 18, 17, and 1 all in one book.
Again, Howey pushes the story in ways that a lot of writers wouldn’t. There are elements in the book that surprised me and which make the series so captivating. I don’t want to write too much in order to not give things away.
So, with that in mind, if you read Wool and Shift, keep on going and finish the series. You won’t be disappointed.