Leaving aside the fact that its leading man is a vile human being LOL. I'm separating the art from the artist. (Something we Buffy fans know a bit about in regards to Nicholas Brendon and Joss Whedon.) I saw the movie and it wasn't a bad film in its own right. It was enjoyable, well made (apart from the CGI) and had great performances. However in the broad scheme of things, IE what it means for the DCEU and the Burton duology, sorry I think it's awful for two reasons.
SPOILERS look away now if you haven't seen it.
The premise is that Barry Allen travels backwards in time to try and save his mother (who was killed under mysterious circumstances.) He ends up however falling into an alternate universe. The one where Michael Keaton's Batman exists. He knows General Zod is invading like he did in Man of Steel. He and the Barry of this universe go to Keaton's Batman and after some reluctance, he helps them rescue Supergirl. After the other Barry gets his powers, the four of them fight Zod, but they lose, Batman and Supergirl are killed, and this earth is destroyed, but Barry tries to go back and stop it and fails every time, which makes him realise that he can't change history, so he travels back to his universe. As he goes through the multiverse, we see images of other universe, which include other DC adaptations, like Adam West and surprisingly Nicholas Cage as Superman, which never happened, but famously there was an attempt to make a Superman movie with him in the 90s.
At the end when Barry seemingly gets home however, he discovers that he isn't in his universe as George Clooney is Batman here.
Now the two things I despise are, 1/ the Keatonverse earth is destroyed. What a terrible ending for the Keaton Batman. It ruins the first two movies. Kim Basinger, Michelle Pfiefers Catwoman, Knox, Commissioner Gordon, all those characters you liked all killed off screen, all Batman's efforts to make Gotham a better place, worthless, the proud shot at the end of the first film of him overlooking Gotham now comes with an "Oh by the way in 20 years it all got blown up anyway".
What's even worse, is that the Keaton Batman's earth wasn't even destroyed by a Batman villain! It almost feels like a parody to be honest. It would be like if I did a revival of Buffy where the Daleks blew the entire earth up 10 years after Chosen.
Why do these people do these types of stories! The Arrowverse Crisis on Infinite Earth's, did exactly this to the 90s Flash, completely destroying his earth and making everything in that show pointless when you watch it back, just for a cheap way of building tension in another heroes story. I wouldn't have minded the 90s Flash dying as a hero, but to blow up his earth was awful. There is a reason No Way Home is so beloved. It didn't shit on the other movies.
It's so annoying because I was so excited to see Keaton working with other heroes. I hoped this would increase my enjoyment of the first two films, being able to watch them and think one day, unlike the other early cinematic super heroes he'll finally be part of a justice league like the comics. Now when watching those movies, I'll have to disregard the Flash entirely,.
Also way to make Keaton's Batman look utterly useless. What he at the end of his career with decades of experience, two Flashes AND Supergirl to help him, can't beat ONE villain that Superman defeated when he was a rookie hero?
What's even worse is it didn't need to happen! We could have had Batman and Supergirl still die and Barry try to save them and fail, but all four still ultimately saved the earth. That would have been enough for Barry to try and change things, the earth did not need to die.
That said however I don't blame the writer for this. I blame James Gunn, which leads me onto my next criticism. 2/ George Clooney as Batman at the end. What a stupid, pointless, worthless cameo. It means NOTHING in the film, except to f*ck up Barry, Supergirl and Batman's stories.
The original ending was that when Barry got back to his own universe, he would discover that the rip he had created between realities and the constant monkeying about with time, had caused both his and the Keatonverse to merge. Both realities still existed, but now certain aspects of the Keatonverse's universe existed in the DCEU and vice versa. (This abandoned plot point is still hinted at when Barry is running through the multiverse and they are clearly beginning to merge together thanks to his actions.)
The original ending therefore would have had Keaton stepping out of the Batmobile whilst Supergirl flies up above, and Barry getting a message from Affleck who was now in the Keatonverse. Granted this is a bit convoluted, but at least it would have ensured that all three heroes stories came to a proper close. Now Supergirl can be a hero after being locked up in her world, Keaton Batman who has come out of retirement gets a chance to redeem himself after turning his back on his duties, and Barry has to face the consequences of his actions. It also could have served as a nice cap off to the DCEU without Justice League 2, as now that the DCEU's history was different, maybe the bad Knightfall future could be averted? Maybe Keaton won't make the same mistakes that Batfleck was destined too because he is older and more experienced? Similarly with Affleck being younger and stronger and perhaps other DCEU heroes in the Keatonverse to help him, its bad future could be averted too.
However Gunn had to come in and cut Keaton's last scene, (because he didn't want it to clash with his own films, which will have their own Batman) and so he stuck George Clooney in as obviously no one will want the series to continue with him instead of Gunn's choice unlike Keaton. This however now means that the two universes have not merged. Barry is now just stuck in an alternate reality, and will never see his loved ones again like the Justice League. (Which is a pretty horrible ending for him too. Also as this is the end of the DCEU, this also means the DCEU is doomed as Barry won't be there to travel backwards in time and stop the Darkseid future) and Keaton and Supergirl are dead and gone forever.
In one foul swoop, Gunn destroyed both the Keatonverse, and the DCEU. Not to sound petty, but a part of me hopes his universe tanks for f*cking up other people's stories for his own shit so much. (Obviously I will still give it a chance, but honestly I resent its existence now when ironically I didn't before. I was ready to say goodbye to the DCEU with the original Keaton ending.)
I think the original cut could have been one of my fave DC movies. There were other scenes that sounded great too that I've heard where cut, though I don't know how true these are, maybe someone could conform them. I heard that Henry Cavill and Supergirl would be shown flying together at the end. (The first time these iconic characters would ever have been in a film together.) Also there would have apparently been a romantic scene with Batman and Wonder Woman, where her lasso of truth made him reveal his feelings about her (to set up the tragedy of them being separated.) Affleck was apparently very proud of it, feeling he had finally got the handle of the character in it.
I hope one day we get a Keaton cut with the original ending and all of these scenes inserted. If we do, then I think that most people will view the DCEU as Snyder cut, Ayer cut of Suicide Squad and the Keaton cut of the Flash.