Batman (Ben Affleck) and Wonder Woman (Gal Gadot) recruit The Flash (Ezra Miller), Cyborg (Ray Fisher), and Aquaman (Jason Momoa) to help save the world from Steppenwolf (Ciaran Hinds), a being banished to another realm after Amazons, Humans, and Atlanteans took away his power by separating 3 boxes called The Mother Boxes. The boxes awaken with the death of Superman (Henry Cavill) from Batman vs Superman (it was too long but after a second viewing it wasn't SO bad) which brings Steppenwolf to Earth. All the Justice League has to do is defeat Steppenwolf before he turns Earth into his childhood realm...sounds simple enough.
I was not jazzed about Ben, Ezra, or Jason being in their roles. And after watching the movie I cannot picture anyone but them in their roles. The casting was perfect; they each bring a different personality to the roles. Barry Allen talks fast and is slightly awkward. Arthur Curry is a slight hothead with a big heart. Bruce Wayne is tired of the billionaire's life and wants to do something else (he was better in this movie than the previous). The only part I hated in this movie is Wonder Woman feels sexualized. There's one scene where she jumps down and you can see the bottom of her butt cheeks. This wouldn't have happened in Wonder Woman...just annoyed by that especially with the state of Hollywood right now.
Joss Whedon co-wrote the script and made it light and funny. Unlike the two previous DC rebooted movies (Man of Steel and the aforementioned Batman vs Superman) there wasn't a lull nor boring humdrum of this film. I loved it alot actually. It felt like Wonder Woman (my fave superhero movie THEN The Avengers).
Go see this movie before it leaves the theater. You won't reject it; especially with the big screen special effects.