I am going to start off by saying this movie isn't for everyone. The original story was written around 1913 and it focuses on some pretty outdated views of mars. The story addresses these in some cases an ignores them in others. They have a walking city being responsible for some of the banding that was seen on mars with early telescopes. This is not mentioned and is left for only those with knowledge of astronomical history or those who have read the actual books. They why and how John Carter can do his physical feats is left for late in the film. Though there is an early scene of him getting used to Martian gravity. This is done pretty comically bordering on hokey.
The action of the film also walks a line of fun and hokey, sometime diving into the later. The look is sort of hyperactive and unrefined. It reminded me a bit of the Yoda versus Count Dooku fight in Star Wars. I personally would have preferred a bit more detailed swordplay. If they ever do an Elric Of Melnibone movie I really hope they go with gritty clashing sword action rather than this style. This sort of one touch one kill action is actually more in line with stormbringer but it just seems goofy to me.
The story was OK, thought pretty convoluted. For some reason The plot reminded me Beast Master with Mark Singer. It just had a sort of plodding going places sort of vibe to it. I know that criticism can be applied to Lord of the Rings but it felt like there was a reason and everything was driving forward. This one seemed to have the back and forth of a legend of Zelda game.
The imagery was great though it really felt fantastic, almost Rodger Dean inspired at times. But without being a lame copy like Avatar, what a piece of shit that was. The airships were interesting if a little like eldar wave serpents. It was inspiring for me as this is pretty close to the look of my ongoing role playing game project.
All and all I am going to say you probably already know if you are going to like this movie. If you like scifi and fantasy you will enjoy it. If you don't care for this sort of stuff then just stay away. If you are on the fence you will be on the fence about it afterward. Probably best at a lower price.