The visual effects were horrendous in most scenes. While visual effects aren't the core of the story for me, and I care more about the plot, some parts of the visual effects are essential to a movie or character, in Superman's case, it's flying. Superman needs to look like he's really flying, otherwise it won't work. No one would 'believe a man can fly', and in The Flash's case, Flash needs to look like he is really running at hyper speed, but he looked anything but that in his actual first movie. On another note though, bad effects aside, I did like the cinematography. It looked good for a DC movie. But looking back at why The Flash failed, story aside, I firmly believe it was ultimately because of Ezra Miller's bad reputation and the announcement of the DC reboot that destroyed this film at having any chance of success.
After rewatching The Flash, it looked like it was a good story that was messed up by James Gunn. I have to admit, every scene felt jumpy. Sometimes, it felt like every second or minute needed to be comedic. The film had a great plot and cool moments. Keaton's Batman was a great inclusion, but I think the cowl really degraded his presence. Miller's younger version of himself was irritating and really stupid. "Why's it so cold?" when he knew they were in the arctic. BAD WRITING. It wasn't even funny. That was probably not as bad as "brunch" though.
The bad things that stood out to me in the movie, were the costumes (Affleck's being the worst one, Keaton's cowl and Miller's main Flash suit...they messed up BIG TIME), the bad running effects, the rushed plot, and going back in time to the beginning--basically meaning none of what we watched develop in the story really mattered because Barry went back in time to undo all of it, except his father's surveillance footage. I thought it was weak to end the movie. I wish they had found a way to actually stop Zod and win somehow even if that meant somehow rewriting the future...it would still suck though because that would also mean 'Man of Steel' never happened. The conclusion was awful. George Clooney shows up and um...the open-ending, or incomplete ending sucked. It felt like a punch in the gut to the DCEU. To think we'd have Momoa's Aquaman back, and...Ezra...but Gunn erasing Cavill and Affleck, not giving a ***k. We know the original plan by Gunn was to keep Momoa, Levi and the infamous Ezra Miller...and Gal Gadot??? (confused)