Okay, so that went largely as expected from the trailers and descriptions, but with some surprises. Mainly, I didn't expect Oliver to die so soon, though I doubt that will stick, since they wouldn't ditch their star player so early in the huge crossover. Also, we barely got any Barry/Oliver interplay, and I think they said in interviews that there will be more of that.
So Earth-89 and Earth-66 are obvious, but why is the Titans world called Earth-9?
So far, this has one of the same problems the original CoIE had, which is that it's just too cluttered. You'd think Nash showing up and telling the sad tale of how he released the Anti-Monitor and is now a Pariah would warrant a big scene, but it's just a random throwaway moment in the middle of Oliver's death scene. Why is he even there? It would've been better to leave his intro for the opening of Part 2. And the bit about Ollie finally learning about the discrepancy in the Monitor's predictions -- telling Oliver he had to die to save Barry and Kara while telling Barry he still had to die -- was far too cursory for something that's been building up for a year. Although on the other hand, it's entirely in character for Oliver to process it so quickly and react so decisively.
It's also quite hard to believe that Oliver staying for a few extra minutes and shooting a few arrows and fighting an army of demons with his bare fists would save a billion people. And why did the Monitor just whisk the others away without asking but not do the same with Ollie?
The antimatter wave makes no sense. Somehow Argo City is the only inhabited world(let) in its path even though it's spreading through the whole universe and destroying everything? And it bounced off the "edge" of the universe, which is infinite in size and has no edge? And even though it's fast enough to reach the edge of the whole universe and back in 5 hours, it's slow enough that you can see it coming and have time to prepare?