I came to this having enjoyed the terribly-named movie version much more than I had expected. Not deep, but pulpy fun. (Seriously, John Carter? "A Princess of Mars" was too girly? "John Carter of Mars" might have, what, given the impression it takes place on Mars?!?) I didn't know how much of the book had made it into the movie, but I was hoping for some of the same kind of pulpy fun from this.
And the book mostly delivered. At times, I was shocked how faithful the movie actually was - things I had guessed had been added in had come directly from the book, including the prologue, and Woola. The Thark storyline was mostly unchanged. The big differences came from the war between Helium and Zodanga, and the guys secretly controlling the Zodangan empire, who do not appear in the book.
This is, of course, a book of its time, and heavily colonial in nature. Both "green" and "red" men on Mars fill the symbolic place of Natives (mostly the Thark, but still, sometimes the red people of Mars too. Dejah Thoris is, in a certain light, a stereotypical Indian princess.) John Carter arrives, and with his military prowess and code of honour, manages to save the civilization of Helium, on the verge of collapse, and civilize the barbarian Thark.
While watching the movie, I thought it was a bit of overkill to make Dejah Thoris a brilliant scientist and
a kickass sword fighter, but I ended up preferring that to the book, where she is there to be clad in thin wisps of material, and be regal when faced with barbarity. As I said, a product of its time. Dejah has immense dignity and pride, but that's about as much as we get of a character from her.
But all of these are general limitations of pulp as a genre, and within that, this book moves along quickly, and immersed me in the action. The world is exciting and filled with peril, and John Carter faces down more enemies than you could shake a stick at. Bravery is rewarded, and treachery punished. The ending notes are some of the strongest in the book, as they give more of a bittersweet ending than a heroic reward.