Warlord of Mars is the third of Edgar Rice Burroughs’ martian novels. For completists, pulpy goodies like Thuvia, Maid of Mars and Chessmen of Mars await.
Warlord is, frankly, weaker than the other two. Burroughs, at his heart, is a frustrated travel writer. His plots have a sort linear propulsion, but his real love is describing the fauna and culture of his fictional Mars (or Barsoom, as the martians call it). Warlord lacks the wonder-eyed newness of A Princess of Mars and theological/cultural fun of Gods of Mars.
Yes, there are some jungle dwelling barsoomians and the long lost, glacial dwelling Yellow Men of Mars (which, by the way is less racist than it sounds; they are described as being literally lemon yellow and seem to be inspired more by Russian kossacks than sinophobic fears of the Chinese). But overall, he didn’t seem to find anything to really capture his curiosity. At least it starts pretty quickly, beginning in media res and rarely halting.