Injustice gods among us is one of the better fighting games I have played. Allowing players to play as one of Earth's mightiest superheroes, you will get different powers based on the superhero you choose.
Not to give too much away but this game follows a very typical DC comics storyline ( with multi universes and what not). Anyway, in story mode, you will get to play as various characters as various stages through the game ( and needless say the three big ones- Batman, Superman and Wonder Woman are all included). My one gripe with the story is that it is way too short and too typical with not much twist and a fairly predictable plot. The storyline could definitely have been extended given the simple storyline and they had a range of characters that go unused through the story. The story can be completed in just a few hours. Finishing that you can test yourself in challenges or better yet playing multiplayer.
In terms of game mechanics, it is a fairly simple fighting game, heavy attack, light attack, super move etc... But what makes Injustice fun is interacting with the environments, blowing your opponent through walls and of course the incredible sense of power when you perform awesome special attacks.
As far as fighting games go this is one of the better ones, so if you are one a fighting game addict you would probably enjoy it.