Well, looks like no one seems to review this anytime soon, so let’s keep this here and hope someone makes a more in-depth analysis while I give my generic one.
Cause I’m bored.

So, Asano is known for writing some pretty disturbing manga, most notable being “Good Night PunPun." I read a few chapters of his "Solanin,"  and I remember feeling bitter seeing hopes being broken so naturally and the characters coping up with it. (God, I hope I pick it back again.) DDDD seems to be his more lighthearted story of all, as in cute girls living through the end of the world.

The first few episodes are spent on world and character building. The grounded narrative offers for some realistic interactions, and the occasional callouts by Oran make fun of tropes and stereotypes, giving a reality check that despite the world literally ending, many people around us are still shit, and all of us are powerless in the face of a world waiting to end. And those that are in power are selfish, flawed, or worse, delusional.

Why this world? Why these characters?

One of the plot points in this show is infinity timelines, and there are potentially more emotional and thought-provoking stories that could’ve been told just by looking at some of these characters.
We have a government conspiracy between Japan and America, a genocidal maniac running in the wild, a solider shouldering the weight of green blood, a cult slowly brainwashing its followers, a journalist who only wants truth, an alien trapped in a human body, a big ass spaceship on top of Tokyo, and more tropes and characters that are waiting to spin their own tale, but Asano wanted us to see these two girls, Kadode and Oran.
Now why is that?

As long as you are by my side

Kadode is a normal girl. She has a father who’s too crooked in his work, a mother having an affair, her boyfriend ready to accept her, liked Isobeyan, and she wants to bang her teacher. Oran is an absurd girl. She is a gamer, has a protective keyboard warrior of a brother who only wishes good things for her, a normal father but no sign of mom, friends who accept her shenanigans, and some absurd past. It’s about these characters settling in a so-doomed world, accepting the not-so-great tragedies, enjoying the not-so-much remaining time, and spectating the oh-so-frightening end of the world. It is the feeling of belonging, something concrete to believe in such a fluid world, something absolute.

I cared more about their friendship than the end of the world. And Asano-san did his best, showing his optimism amidst a tragic world.

The animation and music are sufficiently well done—nothing exceptional, though. The voice acting is good; both new and pro VA’s gave their best. I had a good time going through an episode per week.