Despite the fact that the reviver did not like the film that much I like it.
Its not a film from the book exactly but made with the book as inspiration – or as its says in the film “A story base on the A Princess of Mars book”.
I have read the books some time ago (quite some time) and I had the expression that the film differs from the film a bit even if one can recognize most of the plot.
The film starts with Net (what John Carter calls Edgar Rice Burroughs in the film) travelling to get the the funeral of John Carter. He then gets from john’s attorney, Carter’s personal journal and the film flashes back to Arizona and John Carters adventures looking for gold after the civil war.
He finds a cave when trying to get away from the Apache Indians and a Thern appears and John kills it, He then manages to travel to Mars, more or less by mistake.
From there, most of the film takes place on Mars, and its only in the end, we returns to earth. I will not go further into the story, but I can say if you Like SF and grand adventures the film is nice and I really loved it. Even of the story differs from the book a bit. If some one don’t like the ending its clearly for the film was planned to be just the first of 3 films based on the Barsoom series of books.