I should preface this by saying: I am a long time fan of John Carter and Edgar Rice Burroughs' Barsoom books. The fact that this movie was made at all made my day, even though I was pretty skeptical of it as a Disney production.
John Carter is the story of a Fighting Man of Virginia, recently graduated from the conflicts of the civil war who is suddenly transported to Mars, where he is adopted (because of his fighting prowess) by the four-armed, green-skinned, two-tusked towering Tharks, and becomes embroiled in a Martian war. Mostly for the love of the fight (because John Carter is a natural born warrior), but also for the love of a woman, Dejah Thoris, Princess of Helium.
As a long time fan, I was totally satisfied. The Tharks looked like perfect Tharks, and Willem Dafoe as Tars Tarkas was possibly the best performance in the film. Dejah Thoris had been rebuilt into a woman who could take care of herself, brains and beauty and a great sword arm. The rivalry and contempt between the Zodangans and the Heliumites was well illustrated when we saw them together -- and Kantos Kan was a great background character. I think he might have been my favorite Red Martian. AND, the framing of the movie as a story told to Edgar Rice Burroughs himself was worked in! (As a fan of the books, I loved this element. As someone going to an action movie though, I could see why it might be frustrating or confusing. It definitely adds an element which requires us as movie-watchers to slow down and have a little bit more patience than we generally would for this kind of flick.)
I was really surprised by Taylor Kitsch. When I first learned that Gambit was cast as John Carter, I couldn't really see it, but from the moment we see him launching himself across a desk to fight his way out of military custody, I was sold. In fact, I had no complaints about any of the casting in this movie. Nor did I feel that the changes made to the storyline of A PRINCESS OF MARS do anything but help to accomodate the translation of the book to the big screen. Everything that was changed (and I won't go into spoilers) felt to me like a natural evolution, because let's not forget that these books were written as serials nearly a century ago. Andrew Stanton kept the essence of what made the Barsoom books wonderful without making us feel as though the story was dated, and more than that, he made the more familiar elements. which were used as source material for every other science fiction/fantasy series since, into something we could see and enjoy with fresh eyes.
All of this said, do not waste your money on 3D -- this movie didn't need it. The visuals are stunning enough to stand for themselves.
And Disney: do not ever insult me again by thinking that including "of Mars" in a title won't appeal to my feminine demographic. But if you were THAT worried about it bringing women into the box office, why didn't you just keep the title A PRINCESS OF MARS to begin with?!
I guess you could say the title was the only thing I didn't like about the movie. That and the marketing. John Carter is not Star Wars for a new generation -- John Carter is the source material from which Star Wars was written.