Transferring a book to the screen is never an easy or simple process. Often, a lot has to be left out... exposition, subplots and plot lines, characters and internal monologue. What can go up on the screen is further constrained by the money and time available, by the talent in front of and behind the screen.
Is this the "Worst movie evah!" Not hardly. If pressed, I'd give that honour to Tim Burton's 'Planet of the Apes', a work which cost more than the previous Apes franchise of five movies and two TV series all put together, but which was appallingly stupid - unbelievable talent and money went into making a painfully awful movie.
On the other side of the coin, here we have an action adventure movie made for very little money, with little in the way of resources. Yet it's amazing how they managed to actually make an enjoyable, watchable film.
I'm not necessarily a fan of Asylum films. A lot of them suffer from the worst sin of film-making, tedium.
But Princess of Mars is anything but tedious. There are no shortage of rocky moments, including awkward scenes with Kantos Kan, and there's definitely stuff to dislike. Shortcuts, or shots where there was no time or money to do more than get something in the can.
But flaws aside, it's a relatively faithful telling of the novel. The biggest changes are the reduction of the role and backstory of Tars Tarkas, and the elimination of the Zodangan war, as well as the cosmetic stuff - short stubby two armed Tharks, riding giant birds instead of eight legged horses.
A lot of the true heart of the novel and the characters remain. John Carter is light hearted and heroic, Dejah Thoris is regal and idealistic, Tars Tarkas is noble. The relationships develop naturally between them, the acting is usually decent and sometimes quite good. The location shooting in the Vazques rocks is a highlight, the place looks genuinely weird and alien. The script, apart from the occasional clunky line, moves quickly and efficiently, there are witty lines.
Frankly, my advice is to go look at the trailer. A lot of times, the trailers are better than the actual film. Or the trailers contain all the good parts of the film and the actual film tends to be mostly filler. In this case, the trailer is actually a good showcase for the film. If you liked the tailer, you'll enjoy the film.
In the meantime, I'm pretty happy with it.