The script establishes that Jason Todd recently died, and it's created a rift between Nightwing (who's hardly in the film at all, only two very short scenes and is a perfect example of an unnecessary addition) and Batman, and caused Batman to lose his purpose.
It also takes a kind of interesting approach with Lex, but at the same time I found his character to not have much depth or be as interesting as he should be.
Besides Lex, the big bad is actually Doomsday, who is cloned by Cadmus from Kryptonian DNA found on the World Engine from MoS. It ends up using the horribly cliched "this is our answer to Superman who won't do what human politicians tell him so we built our own but it broke our control program and went crazy" plot device and was an unimaginative disappointment. Also, Superman dies at the end, so it's heavily influenced by the Death of Superman arc from the comics in that regard and Doomsday's inclusion.
John Stewart is in it, and is already a Green Lantern, but doesn't actually show his Green Lantern powers and instead rights Doomsday with a gun and soldiers and tanks (which is completely illogical). At the end Superman's body is at STAR Labs and Stewart is there and is contacted by Kyle Raynor through his ring, Hal Jordan is also mentioned, Guy Gardner is also in the script but isn't a Lantern yet, just a cop. During Stewart's conversation with Raynor, it's mentioned Darkseid is coming to Earth, so I guess that's the villain for Justice League (assuming the script isn't changed majorly by Terrio's rewrite).
Victor Stone is in it, as well as his father Silas who works for STAR Labs and helps Superman. Victor is severely injured by Doomsday during the end battle scene (part of which occurs at the football stadium where Victor is playing in the game), obviously setting up Victor becoming Cyborg in the Justice League film.
Obviously Wonder Woman is in it, and she comes to Metropolis to rescue one of her Amazonian sisters who has been captured by Lexcorp. It's later implied the Kryptonian DNA they used to create Doomsday was supplemented with Amazonian DNA. She also joins Superman and Batman in the final battle against Doomsday.
Aquaman was not in the film script, though other Atlanteans were, but only in the opening battle scene. I'm assuming this means Aquaman will show up in Justice League, again unless that's something else Terrio alters.