Considering the budget that must have gone into casting for this film -- and featuring nearly every Batman/Superman character since the birth of Methuselah -- the overall production was really poor. Ezra Miller as the lead -- initially awkward, which he's known for, then gradually coming out of his shell as Flash/Barry -- is fine, but the storyline is extremely convoluted (no spoilers for those who have the time to go watch the movie). Seeing our favorite Batman(s) was nice, but Cavil's obvious absence given the multiple Batman/Superman cameos made the film extremely awkward and ridiculous. Of course it gives Keaton a bit more time to shine -- no complaints there. But the reported excuses of "confusing viewers" with too many Superman cameos when they basically threw in everything and the kitchen sink into the movie tells viewers that this is simply hogwash.
No spoilers to the plot. The plot will spoil itself.
No spoilers to the plot. The plot will spoil itself.