I've got the CW app and it labels these episodes as COIE 1-3 so I'm not sure, but I think they are actually episodes of Supergirl, Batwoman, and Flash, in that order. Last night's part 3 ends with a mini-cliffhanger and it looks like parts 4-5 won't air until next month. Although tonight there is supposed to be a Black Lightning episode that ties in as well, somehow. Or maybe I'm a day behind.
I'm watching these mostly as a fan of the COIE comic and the DC comics in general. I tried watching some of the Arrowverse shows a season or two back and couldn't really get into them.
One of the interesting things is seeing the various cameos from past DC adaptations but they are unfortunately too brief. Burt Ward, dressed in plainclothes, is he even supposed to be Robin? He simply looks at the sky and says "Holy red skies" or something (no "Batman"). For some reason Robert Wuhl as Knox, the cameo that no one asked for or expected, but okay, looks up at the Batwoman-signal and says "I hope you're watching, big guy" ... is there a Batman on Batwoman's Earth? Jonah Hex, I assume he's the one who appeared on Legends, but he doesn't really act like Hex. Jim Corrigan/Spectre, did he appear with the JSA on Legends? It's interesting, now that Smallville is part of the Multiverse, you could have any and all characters that played either the JSA or Legion from either Smallville or Legends appear, you could mix and match, whichever actor is available. Will we see Lobo from "Krypton?" Swamp Thing? Ashley Scott's Huntress appears on a rooftop just to be erased by anti-matter. Dina Meyer's Oracle only gets a voiceover.
Lots of familiar images from the comics which is good. Red skies, antimatter waves, shadow demons, tuning forks, anti-matter cannon that the Flash destroys at the cost of his own life. Monitor murdered by Harbinger who has been infected by the Anti-Monitor, just like the comics. I assume the resolution of the cliffhanger will be that the last few Earths were not destroyed but saved in a pocket dimension by the Monitor as a failsafe, like in the comics. But instead of the battle at the dawn of time we have Vanishing Point and the Waverider, so we may be pulling some ideas from Zero Hour as well?
Too many distractions. Luthor hunting alternate Earth Supermen with the Book of Destiny, a completely new plot jammed into an already busy crossover. The plot to resurrect Green Arrow who died in the first episode, we spend an episode resurrecting his body via Lazarus Pit and then an episode going to Purgatory to retrieve his soul, only for Oliver to decide "no, I'd rather stay dead." Kind of a waste of time, like the casino planet in The Last Jedi. I guess they needed to justify appearances by Constantine and Lucifer.
Monitor sends Batwoman to an alternate Earth to retrieve "The Bat." She finds Bruce Wayne (Kevin Conroy) who I guess is evil, and immediately kills him? She returns in defeat only for Monitor to say "The Bat you had to find was yourself." Couldn't he just tell her that? How did killing Bruce help her? She needed to find the "courage" to kill her mentor to become the Paragon of Courage? If that was the point, it should have been more emotional. The writing and acting is very surface-level in these, I wasn't feeling it.
Pariah seemed like he was mostly in the comics as a way to guide readers to Earths that the story wouldn't otherwise take us to, like seeing the destruction of Earth-3 and Earth-6. He's not really used for that purpose in the CW version and I wonder what his purpose will be, but being that he's played by a series regular, he will probably figure into the resolution in some way he didn't in the comic.
Missed opportunities: When Superman and Lois sent their baby off in a rocket just before they were destroyed by anti-matter, it was reminiscent of Earth-3 Luthor and Lois doing the same in the comic. Their baby, rocketing through the anti-matter wave, became the hybrid matter/anti-matter being Alexander Luthor. But in this version the Kents' baby just gets diverted to another Earth and saved a couple of scenes later and the Kents are as well. So we get Harbinger and Pariah but will we get the other two new characters from the COIE comic, Lady Quark and Alexander Luthor? Probably not.
All in all a mixed bag, but an A for effort.