A major character of the saga who appears in this novel is the Trader, who apparently goes off to die alone near the end of the book, but is constantly referenced in future novels. It also brings Doc Tanner (a senile-sounding gentleman with knowledge of pre-war America) to the group, and gives us our first glance at one of the series' long running mutant menaces : Stickies.
This book also introduces the Redoubts, in particular the Cerberus Redoubt, and the MAT-TRANS teleport chambers that are a major plot device driving the series.