So here's the checklist of what goes into enjoying John Carter.
Do you like SF action films?
Do you know what the pulps were? And are you okay with seeing them in movie form?
Did you know that the Barsoom series (what the film is based on, just in case you didn't know) was published more than 50 years before the first Star Wars film?
If so then i think you'll like this movie.
Oh, and also, do you like hot women who kick ass in valkyrie armour? If so that's definitely a bonus.
And finally as an aside, it didn't hurt that every trailer before the movie looked awesome. "Battleship". "The Hunger Games," "Prometheus", "Men in Black 3", "Brave", "The Avengers." I don't expect all of those movies to actually be good (i'm looking at you, Milton Bradley boardgame) but as trailers leading up to an action film they served their purpose very well.