John Carter is truly the Rajnikanth of Barsoom (Mars). Aided by a low gravity of Mars, he is seen skipping the surface, literally flying in the air to dispatch a throng of soldiers in order to save a damsel in distress. In The Princess of Mars by Edgar Rice Burroughs, Carter has no compunction in killing or causing mayhem in general. While reading it, I constantly felt that maybe this book is the mother lode of all South Indian Movies and their Hindi Remakes which are thrown in our faces today, with self-obsessed and quite vain Superheroes, slobbering crowd of permanent admirers, a highly dependent and quite naked heroine, a lusty super villain and various sidekicks whose only job is to lie prostrate on the ground, waiting for the enemy sword, only to be saved by John Carter in the nick of time.
I initially had a bit of difficulty in digesting the fact that a book revolving around a Confederate soldier would garner that much adulation pan America. So I trawled the internet for a suitable explanation. I found that people wanted him to be a Confederate soldier, with a certain set prejudices so as to lull (and allure!) a certain section of society with resonating beliefs and try to reform them by showing them how John Carter acted as a uniting force/superglue (though all he cared about was the Princess!), who brought together two warring races with remarkable differences in their physical features. I want to believe that explanation.
I found this book highly entertaining. Spanning over just 186 pages, with at least one horrific death per page, this book is indeed bang for the buck. Yet I wouldn’t go as far as calling this book, a science fiction, it is science fantasy at best. But I am being unduly harsh here. This book was written way over in 1912, it is indeed a pioneering work. It has inspired an entire generation to shoot for the stars, and books like A Princess of Mars have acted as catalysts to quicken the pace of science.
If you are looking for an entertaining read, this is the one…
Alienman 
There is a specific term for the sub-genre of SF which includes “A Princess of Mars” and similar stories. They are called “Planetary Romances”.