The Crisis trilogy was better than I expected. I felt it would be redundant after the Arrowverse Crisis, but it managed to tell a very distinct story with different emphasis, and drew on elements of the original story that the Arrowverse version didn't or couldn't adapt (like a certain iconic cover image). I felt successive installments got weaker, but the first one had a strong core story about the Flash, and the second one told a nice story about Supergirl. The trilogy also retroactively brought more unity to the Tomorrowverse, picking up continuity threads that the previous movies skipped over. One of the Tomorrowverse's biggest flaws was that it was barely a series, just a scattering of self-contained stories with only cursory continuity nods here and there. This concluding trilogy tied a lot of plot and character threads from the previous movies together and gave it more unity, even if it was too little, too late.
I liked the choice of Supergirl as Harbinger and Constantine as Pariah, tying those roles into established characters and building on their storylines to give more weight to the CoIE characters/elements. The Monitor learning empathy through caring for Supergirl was a lovely story. Using Constantine to tie the Tomorrowverse directly into the previous animated continuity, making it retroactively all one series, was an interesting choice, although maybe an unwise one given what an anticlimax the unfocused, hit-and-miss Tomorrowverse was after the generally strong and well-unified Animated Movie Universe. Especially since the climactic revelation is Constantine admitting it was a mistake to create the Tomorrowverse in the first place.
I did find it odd that the story relied on the premise that the multiverse shouldn't exist and needed to be wiped out. It's close to how the original comics did it, but these days multimedia franchises seem to be all about embracing the idea that their various different screen continuities are alternate realities in a multiverse, like the 2014 TV Flash meeting the 1990 TV Flash, or the Tom Holland Spidey meeting the Maguire and Garfield Spideys. Of course, all these multiverses don't really reconcile with each other at all -- for instance, there's no way to reconcile the multiverse physics of the DCEU The Flash with the Arrowverse -- but it's surprising in the current media climate to see a story come right out and explicitly preclude the possibility that its multiverse could be reconciled with others. Although that kind of contradicts it tossing in the Super Friends and the DCAU as parts of its multiverse.
I did find it odd that the story relied on the premise that the multiverse shouldn't exist and needed to be wiped out. It's close to how the original comics did it, but these days multimedia franchises seem to be all about embracing the idea that their various different screen continuities are alternate realities in a multiverse, like the 2014 TV Flash meeting the 1990 TV Flash, or the Tom Holland Spidey meeting the Maguire and Garfield Spideys. Of course, all these multiverses don't really reconcile with each other at all -- for instance, there's no way to reconcile the multiverse physics of the DCEU The Flash with the Arrowverse -- but it's surprising in the current media climate to see a story come right out and explicitly preclude the possibility that its multiverse could be reconciled with others. Although that kind of contradicts it tossing in the Super Friends and the DCAU as parts of its multiverse.