I'm a huge fan of the books, also of Tarzan, the Venus series, the Pellucidar series, basically anything by Edgar Rice Burroughs.
-but I haven't seen John Carter. I'm guessing it's terrible.
I imagine it's something like Prince of Persia or Pirates of the Caribbean- fun action vignettes strung together on a forgettable plot.
"Pirates" wasn't really my thing, so from my point of view, Disney has made three good live action movies since the seventies, Tron, Return to Oz and The Rocketeer.
A really terrible track record.