Perhaps the single most significant thing to keep in mind when reading A Princess of Mars / John Carter: Mars Series #1, or watching the Disney film John Carter, is that the Edgar Rice Burroughs novel (and the Barsoom series) came first. Not simply before the film was made in 2012, but before most of the Science-Fiction and Fantasy works you are inclined to be reminded of as you make your way through the story.
According to Wikipedia It was first serialized in the pulp magazine All-Story Magazine from February–July, 1912. So, as you make your way through the novel, or watch the movie, each time you are tempted to think, “I’ve encountered this before” stop yourself for a moment, and rephrase that thought… instead of being disappointed in a Darth Vader like moment, wonder instead if the folks who brought your Darth Vader in the 70s, did not perhaps encounter John Carter, the Barsoom series, and the Princess of Mars on their way to making the Star Wars films. When John Carter is taking a giant leap for Mankind, consider for a moment how many members of NASA, from those who never leave the Earth, to the Astronauts who have sent us messages from their trips to the stars, were inspired by Science Fiction, and the works of authors like Edgar Rice Burroughs.