Mixed reactions. The time-travel stuff did not make any sense at all. If Thawne changed the timeline by getting himself struck by lightning in 2013 and killing Barry as a child, why did he also need to change it by killing Joe and sabotaging STAR Labs in 2021? And why weren't any of those earlier changes reflected in the 2021 timelne? That's utterly incoherent. Also, since when did the Flash running around the world cause global cataclysms? Didn't he and Supergirl both run around the world at superspeed at the climax of Elseworlds, without any kind of global devastation? Not to mention that Mach 20 seems pretty slow for creating a time vortex.
On the plus side, I loved how they used Damien Darhk. It made sense that he'd still be villainous (and alive) in this timeline, but he was still true to his previous characterization, with his love for Nora being the thing that redeems him.
Mixed feelings about the ensemble, too. It was good to finally see more than one guest star in the episode and have some real team interaction, but the amount of character progress seemed more consistent with one or two years than a whole decade. I'd been looking forward to seeing Ryan Choi again, but I didn't like his altered characterization, no longer a family man in this timeline. And while we finally got to see him in a very authentic Atom suit, I'm pretty sure it was just a repaint of a Flash suit, with the same distinctive construction and texture to the cowl. Plus I was hoping we'd get to see the official handoff of the Atom mantle from Ray to Ryan. Still hoping that happens next week in the real timeline, but I'm not betting on it.
Maybe Jesse L. Martin wasn't available due to some other project, or maybe they only signed him to appear in a certain number of episodes this season to save money. That might be why they wrote the storyline around his absence in the first place.
It's not a real victory unless you can gloat.
When you time travel, you go outside of time
If you're out side of time when the time line changes you enter the wrong timeline.
Every time the timeline changes, every time traveler enters every timeline, because they are always outside time about to reenter time.
Of course that doesn't explain how Barry got home to a 2021 where Thawne was not the Flash?
Unless there are infinite Barry Allens, traveling to infinite 2031s, and then traveling back to infinite 2021s, and Berlanti just cherry picked the stories he wanted to see.
Why did Barry have to go Mach 20?