This is meant to be the origin story of DC Comics' version of the Knights of the Round Table (or, I don't know, the Avengers?). We've met the current Bruce Wayne/Batman (Ben Affleck), Clark Kent/Superman (Henry Cavill), and Diana Prince/Wonder Woman (Gal Gadot), but they need a few other superheroes to pick up the slack when they are tossed through a wall or thrown off a cliff by the new bad guy in town Steppenwolf (voiced and maybe acted by CGI-covered Ciarán Hinds).
Steppenwolf is from space (?) or mythology (did he say that Amazon Queen Hippolyta was his mom and banished him for being evil? I may have misheard) and is power-hungry and has an army of flying zombie/vampire/bugs with nasty big pointy teeth. Steppenwolf has a head like a devil, and even chin horns (and stubble! how does he shave around the chin horns??). Steppenwolf wants to find these... magic boxes? And when you put the magic boxes together, you rule the universe? Anyway.
Enter additional new heroes: Victor Stone/Cyborg (Ray Fisher) was a college star who was cobbled back together by his scientist dad after an accident that should have killed him. Cyborg gives good eye, but is otherwise Robocop fueled by alien (?) technology. Barry Allen/The Flash (Ezra Miller) is a dorky young man who can go really fast. And Arthur Curry/Aquaman (Jason Momoa) is apparently now a tattooed bro who seems to fly more than swim. Booyah.
Justice League feels cobbled together, and the villain plot is more confusing than strong (magic boxes? giant tentacles coming out of a nuclear reactor?). But there are several good action sequences that give various characters a chance to shine. Wonder Woman is awesome, of course. Plus, if you liked the Amazons in Wonder Woman, you will be delighted to see badass Hippolyta (Connie Nielsen) and her woman-army try to stave off Steppenwolf in an early scene. I also appreciated the messed up way that the resurrection of Superman is handled (remember he was dead?). Fans will be pleased that Superman literally explodes out of most of his clothes when he rises from the dead, which entails Henry Cavill to fight shirtless for a whole sequence. (Yes!) And quirky Ezra Miller steals every scene as soon as he opens his mouth (can we shake up the comic universes and put him in a movie with Deadpool?).
More wobbly is the hot but odd character of Aquaman, who I think mainly exists to have Jason Momoa appear shirtless and wet. Except he is usually not near water, but is flying around with his trident. Huh. Cyborg makes a good if small impression (I kind of felt like he was the "token", if you know what I mean). And Ben Affleck grumps around and gets bruised in his thick rubber suit. (Oh, and can someone make that stoooopid gravelly Batman voice-alteration go away?) But the weirdest weirdness is that Henry Cavill's face doesn't look quite right half the time, in a super-distracting "is he actually CGI?" way. [Turns out his face WAS CGI part of the time! Read about the fascinating moustache debacle.]
The last multi-character DC Comics outing, Batman V Superman, set the bar pretty low, so it was kind of hard to not improve. Justice League is certainly better, and I'm pretty sure most people will agree. But I still feel like DC is lumbering along like Ben Affleck in his thick Batman suit trying to catch up with comparably effortlessly entertaining and well-made Marvel films. But this film gives it at least some better momentum.