So I've been curious about the new movie. It's gotten some bad press, like The New York Times panning the marketing effort in "Ishtar" Lands on Mars...but the NYT is generally a bastion of foolish snobbery against genre fiction, especially science fiction or fantasy. The word-of-mouth is pretty good. Erik Mona praised the movie on FB, James Maliszewski points to the clear influence of Barsoom on Gygax. Michael Chabon, interviewed on io9, loved the books too.
But of course it wasn't until I learned that Paul Frommer worked on the Barsoomian language for the film that I started getting really interested. Clearly the creators cared enough about the source material to treat it better than Star-Warsy gobbledygook. The words in the Barsoom novels are not a language, not even a systematic naming language, so it's great that the filmmakers hired someone to expand that linguistic writing and make it more systematic. The novels are dated, and do tend toward juvenilia, but E.R.B. did a lot of underappreciated work in worldbuilding, including fun little elements like jetan. Perhaps Barsoomian was E.R.B.'s linguistic handwaving, a version of the "universal translator".
Fiat Lingua has an interview by Swedish E.R.B. collector Fredrik Ekman with Paul Frommer (PDF). Frommer explains that his expanded Barsoomian is nearly isolating, with very little inflectional morphology. There's no case marking, and the language instead relies heavily on word order. Barsoomian uses VSO, which is a nice choice to avoid re-lexing English, and is a logical, underappreciated word order in conlangs more generally, IMHO. Possession is as in Indonesian/Malay: the possessor follows the possessed with no special marking. Frommer based the language on the 400+ words pulled from the books, mostly names, interpreted into a coherent system. He made some interesting choices, such as including a voiced velar fricative alongside the rhotic alveolar approximate of American English. The most interesting feature is certainly the pronominal system:
Perhaps the most interesting feature is the pronominal system, where there are distinct cases for subject and object (akin to English I/me, he/him, we/us, etc.). To form the objective case, you take the initial consonant of the pronoun and repeat it at the end of the word. So I = tu, me = tut; he = ki, him = kik. Then to form the plurals of these pronouns, you simply “voice” the unvoiced consonants—in these examples, t becomes d and k become hard g. So we = du and us = dud.There's also some good discussion of Frommer's method and the training of the actors in "John Carter: Inventing a New Language". Willem Dafoe discussed his experiences playing Tars Tarkas with io9, with a nice video clip of him speaking a line (at about 03:29).
Pagelady has transcribed some phrases from the movie, and links to this lexicon at Langmaker (by Jeffrey Henning), culled from the same source material Frommer used. The Conlanging Librarian also has a number of posts exploring this material.
Some graphic designers at Disney came up with a "Martian alphabet"; it's pretty unsophisticated, a simple substitution cipher. And it's exactly the sort of this a graphic designer might make to look "alien" but no-one would ever use to actually write with: it would be a nightmare trying to write those characters at speed with a pen and paper, or any other tool other than a keyboard and mouse. But they have a "Martian Translator" to cipher texts and a "Martian Decoder" to decipher them; there's also a PDF. How to Count in Barsoomian has an overview of the numerals of this script.
I don't have time to read fiction these days, but Librivox has the first five books available as M4Bs or MP3s: