Within just a few minutes, the events of Injustice unfold to include the Joker killing Jimmy Olsen and Flash, destroying Metropolis with nuclear weapons, and Superman unintentionally causing the deaths of Lois Lane and their child, as well as physically striking through the Joker. While I’m not particularly attached to Jimmy or Flash, nor especially fond of Lois, it's still a very dramatic start. Beyond his unusual cape, Superman develops facial hair for a single brief scene, which seems intended to signify that he has relaxed his moral standards. Superman declares that he “won’t be held back by ideals that don’t protect the innocent,” and along with Wonder Woman, essentially seizes control of the planet, pressuring Israel and Palestine into an agreement ("Peace by punching," according to Green Arrow). This creates a division within the Justice League, pitting Batman, Catwoman, Plastic Man, Nightwing, Green Arrow, and Harley Quinn against Superman, Wonder Woman, Cyborg, Robin, and Ra's al Ghul, who has joined forces with Superman to cement his turn to villainy. Injustice manages to be both ridiculous and violent while also being enjoyable to watch, largely due to its traditional animation style and witty writing—the cleverness is evident in the dry dialogue as well as a surprising final reveal that demonstrates Superman’s greatest fear is himself (and explains the cape). Similar to All-Star Superman, Injustice manages something uncommon: making Superman compelling. He's still an all-powerful, immortal being, but the film acknowledges his inherent goodness ("your will be done," Wonder Woman observes). By sacrificing his usual strong moral compass, the movie makes Kal-El more surprising and less monotonous than he typically is. Although Injustice’s uncompromising nature loses some of its weight when you realize there are “infinite Earths” with infinite Jimmy Olsens, making what happens in one relatively unimportant; this logical inconsistency shouldn't detract from your enjoyment of the film.

Source on TMDB