I'm gonna say it... despite all the controversy and such... I found this a fun film! And a better send off to the Synder-verse than it deserved.
In that classic story line that seems to dominate Barry's origin now, back in the past his mother was killed and his father sent to prison. So what else to do but go back in time and change that? And see a lot of badly CGI'd people around you at the same time. Like, it takes time for effects and they put the effort in, but that was really bad CGI there... Anyway, as you expect, changing the timeline has some problematic results, and so Barry encounters previous movies and sees others that never happened, until he has to accept that he is the biggest monster of them all.
Having complained about the CGI I will compliment that they did really well with compositing Ezra in both his places. It sold me all the time, and I was looking for discrepancies! (A common one is eye-lines not actually acknowledging that the other person is the same height, but didn't pick up on any problems there.) That would have been a lot of work so well done on all concerned for getting that right.
Michael Keaton as Batman... moderate success. He just looked old and over it, so when his action scenes happened, you could tell it was more stuntman than birdman. And I did have a hard time buying Sasha Calle as Kara. Yes, she was a more beaten up version, but... it really felt like "we don't have Superman, but perhaps you won't notice".
And yes, I laughed at the alternative versions. I hope we were supposed to, because they were injokes galore, so I got them!
But, as I said, overall I enjoyed the story. I thought it was well done, without introducing random villains for moments that would have had them had this been a TV series (Hello CW Flash... who sadly didn't get a reciprocal appearance...), but now that people have had their final cameos, let's move on to other pastures.