There's a lot to admire about this show, but it's a slight miss for me. Quirky, charming, weird, dark, post-apocalyptic... yeah, it's all those. More importantly, though, its obstacles are external. Our heroes are trekking through the end of the world. It's a story about trying to survive giant bugs, tree roots and limited water supplies. There's nothing wrong with that, per se, but the show's challenges don't really involve other people. The drama, such as it is, isn't "character vs. character" but instead "character vs. impersonal non-sentient giant thing".
Admittedly, Rin has a habit of threatening to kill Wakaba. She's so determined to protect her sisters that she's forgotten the balance of "perceived danger" vs. "could be useful". If a basket of kittens appeared before her, they'd be dead meat. Broadly speaking, though, this is a charming little tale of eccentric, not-quite-human people pottering cheerfully through an absolute freaking nightmare. People have called this the real sequel to Kemono Friends and the similarities are undeniable, but Kemono Friends was fluffy. The dark undertones couldn't shift that. This show's fluffiness, on the other hand, is whistling in the dark of "everyone could die at any moment".
I should explain the Kemono Friends reference. With that show, TATSUKI turned a no-hope franchise into the season's surprise mega-hit. The producers then had an attack of the mega-dicks and fired him from Season 2, so he made this show instead. Both are deliberately crude-looking CGI anime about a good-natured, amnesiac human protagonist exploring a post-apocalyptic Earth and its whimsically odd inhabitants. Naturally, the fanbase went ballistic and there was a lot of satisfaction when the non-TATSUKI Kemono Friends 2 sank without trace.
Incidentally, TATSUKI made an earlier version of Kemurikusa in 2012. Kemono Friends was borrowing Kemurikusa's ideas, not the other way around.
What's it like to watch, then? Well, it's a bit disorientating. I watched ep.1 twice, because I had no idea what I'd just seen and I wanted to process it properly before continuing. There are red bugs that are generated by smoke that might be associated with giant roots, in a mostly black world where colours have different characteristics. Red will try to kill you. Green will create tentacles that let you turn half a train into a giant earwig, or at least that's how Ritsu uses them. Yellow is SPOILER.
Meanwhile, the only people still alive are a group of impossible sisters who all have the same hair. The Rinas can bud off copies of themselves and it's possible that they sometimes combine into a single body for laughs. (It's not clear. Maybe they're just standing perfectly behind each other, in line with the camera?) Rin is super-strong and has a ponytail that hangs upwards. Ritsu has those green tentacles. They think at first that Wakaba is a bug (so should die), then later point out that he can't be human because his blood is red.
They're nice, though. Yes, even Rin, underneath. She deserves all the names that Shiro calls her, though. This series is a warm, comforting road trip through world-eating bug hell, as the girls cheerfully discuss who'll die next and tell Wakaba that it'll probably be him. (He's philosophical about this. He never stops being excited about exploration and discovery, which repeatedly saves everyone's lives.)
It's a sweet, kind show. It's portraying optimism and mutual support in a setting that you'd expect to be used for the usual bleak, lazy pessimism. Similarly, its visuals are really strong. These simple CGI models are far more watchable than the uncanny valley of a Netflix or a Polygon Pictures, while the world they're exploring is atmospheric. The only thing this show falls down on, really, is the fact that its drama is basically just "heroes vs. impersonal environment".
Alas, for me that's a significant minus.