The plot is pretty frail, borrowing heavily from Mad Max. But the real purpose of this movie is to serve as a "greatest hits" for the series, showcasing fight scene after artery-busting fight scene.
I’m tempted to say that this is targeted to kids and give it a pass on those merits, but that would be a slight to younger viewers who could be exploring richer DC productions from the back catalogue like JL:U or Batman: The Animated Series.