That's a pretty good take. My concern about so many villains is that it could be an Arkham City type situation. That game got a lot of critical praise, but to me the story felt very shoehorned. Lots of, "hey look, it's Two-Face!" "Uh oh, the Penguin is here!" "Hey, remember Ras al-Ghul from the movies?" Kind of a who's-who of villains, in a forced way.
If it gets at all hammy or pretentious, I'm out. Don't make it like Suicide Squad, where everyone gets a poster and an in-your-face clip, but at the end of the day you're wishing it had about 4 less characters and less sloppy dialogue.