That was always the plan. Affleck has wanted out for a while, and while nobody has been officially confirmed yet as his replacement, I'm pretty sure that's the last time we will see him as Batman.
I thought it was a 7/10 for plot, acting and humor, but will give it a 6/10 for the abysmal CGI.
I was pleasantly surprised as traditionally, DC movies haven't performed all that well so my expectations were a little low, but it seems like they're starting to slowly get a little better as marvel movies start to get a little worse.
There are definitely areas they could have improved upon, of course, firstly, the CGI was just so bad, like the scorpion King levels of bad in some places! The script could have been tightened up a little bit better. It was as if I had to make the jump between a couple of scenes based on my experience with other movies. For instance, when he was talking to his dad in prison, and he quickly transitioned to standing outside of his old house, I thought it was a flashback, or an out-of-body experience or something, but no, he was physically there, seamlessly handed off the phone call from his cell phone to his suit, and it took me a second to figure out what happened. Just a lot of little stuff like that took me out of the movie and forced me to figure out what was happening and re-engage.
I really liked it! The CGI was really bad in points, but I mostly forgave it because of the surreal context. Except for maybe the bad CGI at the end, that was harder to forgive. I also couldn't get out Ezra Miller's various crimes out of my head completely during the movie. I did for a lot of it, but not as much as I had hoped lol.
Still, I really liked it! I thought the story and acting were great. The cameos were enjoyably nostalgic. The heroes got to do cool action stuff while still keeping the enemies intimidating and a threat. And it was pretty funny while still managing to maintain a lot of heart. It's hard to do stuff with the Flash because he's so OP, he has to be pretty dumb to not trivialize every encounter, but they made the battles and action scenes work. I'd probably rate it higher than others who are bothered by the CGI or other personal scandals from the cast, let's say an 8/10.
I also found it a little difficult to get Ezra Miller's various crimes out of my head. I had to keep reminding myself to just enjoy the film and not think about the actor lol. I did kinda end up enjoying the movie though. 6.5/10