It has two problems as I see them, and they are very much related. First, it has a plot. Moreover, the plot is somewhat involved. Even more amazing, is that they were pretty faithful to the source material. Naturally, they were punished for this. Apparently, audiences today want razor-thin plots that marginally related to the esplodey bits.
With this complicated plot problem, this led to problem number two. How do you market it? In general, I have begun to avoid trailers and all other marketing material. Thus, I only have a thin idea of how this movie was marketed. I just know, that naming it John Carter was a huge mistake. How many people are going to know about the Edgar Rice Burroughs source material? Not enough to make this movie a hit -- or at least profitable. So, you have to tie it to something that people can understand. I am thinking they did not do that.
I have even seen the 2009 Traci Lords movie Princess of Mars. They essentially tell the same story. This movie is far superior to that one, but the Disney movie had a much bigger budget. There were several faces that I recognized in this movie. McNulty from The Wire, and Caesar and Marc Antony from Rome. The voice of Willem Defoe was there too. So, the cast wasn't shabby by any means.
If you do not want to know about the basic plot of the movie, you will want to stop reading. I am probably not going to give anything away, but just in case...
John Carter is a former Confederate soldier on Post-Civil War era Earth. He makes a discovery and is transported to another world -- Mars. The source was written in an era when people believed life existed on Mars. Now, we have greatly explored Mars, and know that is not true. So, what do you to be true to the source? You keep it Mars. I think this is why they stripped the "of Mars" from the original title -- a dumb move in my opinion. Anyway, John Carter finds that Mars is experiencing its own civil war, and he does not want to get involved (for obvious reasons.)
Try as he might, he ends up getting involved anyway. You see, he also has super Martian powers. (It has been said that he is the inspiration for Superman.) Hence, his services are desired -- by the Princess of Mars, Dejah Thoris. A love interest, and they win the war and they all live happily ever after. But wait, there is a twist! There is another party that was spurring on the Martian civil war. They complicate the plot. They complicate the ending. They make this movie unacceptable to the Michael Bay crowd. They also make this movie more interesting than the Traci Lords version.
By attempting to stay true to the rather obscure source material, and attempting to update that material, they doomed the movie. Add to that the poor marketing and the ineptness of Disney in understanding what the production team was trying to do -- this movie did not have a chance.
I am not saying this movie doesn't have its problems. I am not saying this movie is great. I will go out on a limb and say this movie is better than any of the Transformer movies. It is also better than Cowboys and Aliens from 2011. I am guessing that the latter probably had a part in the poor performance of this movie. (Again because of poor marketing, but similar in tone, period, and topic.) This movie was fun, and interesting, and did not have a dirge of CGI things fighting each other CGI things for long stretches. There is a fantastically brief battle between two characters that was a breath of fresh air. Overall, I would recommend it for those that like action movies or Sci-Fi fantasy movies.