I've seen Paz Vega in two movies and she was indeed striking. She was in Triage, as Colin Farrell's wife/Christopher Lee's granddaughter. It was a good performance and she was certainly attractive, but it wasn't the lead. She shared lead with Simon Baker in a thriller called Not Forgotten. She was nicely theatrical in that one, but I don't think Sarah Bernhardt could really have sold that character.
John Carter was fairly entertaining. There is a really bungled up wrap-around story, which gives us about four starts to the movie. That's worse than four false ending, by far. Poor old Bryan Cranston has the thankless role playing the Yankee antagonist in Carter's stupid backstory. This was apparently added to give the hero requisite baggage and add an element of reluctant hero, even redemption, to the story line. Just being on another planet should make someone a reluctant hero, it being perfectly sensible to get into what you don't understand. As for needing redemption, being a Confederate provides enough need for redemption without any witless drivel about evil Yankees burning your wife and child alive, which is what the idiot backstory implies.
There is also a basic problem with airplanes and other advanced tech combined with swords and muskets. Plus, we know Mars isn't someplace a man can breathe. Willing suspension of disbelief can be hard to come by, but SF fans are usually desparate, and the Edgar Rice Burroughs nostalgie factor helps.
Taylor Kitsch seems like a man who really would try to help someone in danger right before their eyes, which is all this movie needs from John Carter. He is the butt of enough humor to take some of the edge off the Mighty Whitey trope (and again, the ERB nostalgie factor helps, unfair though this might be.) Lynn Collins is quite fetching. Mark Strong has the hapless task of representing the pointlessly evil villains.
I think overall the best way to think of this is that someone for once tried to make a sow's ear into a wallet, instead of a silk purse. That may be damning with faint praise, but this was better than movies like Thor, Green Lantern (which I thought unengaging but not a bit awful,) X-Men (pick any sequel,) Transformer movies, etc.