Season 1 - excellent
Season 2 - watchable
OVA - WAT

Spoiler - this is a review of the whole series

I’m sorry, wtf did I just watch? Tsutomu Nihei is an auteur in his own right, but his first foray into “approachable” storytelling is…misguided, to say the least.

His corpus consists primarily of non-verbal communiques: the characters are mysteries that begin to make sense over time without any legitimate exposition. Words are a treat, and are few and far in between in one of his OG mangas. The story is usually driven by hard-to-follow explosions and well-illustrated-but-confusing fight scenes set in a random building straight out of an architect student’s wet dream.

Knights of Sidonia, however, is a step away from his usual genius in favor of actual garbage. This bizarre attempt at turning “Gargantia on the Verdurous Planet” into a harem story is a LONG way away from Blame!.

As a first foray into writing a character-driven story, KoS isn’t bad, but by the gods it isn’t good, either. Tsutomu Nihei should have stayed in his lane and just delivered another arcane epic driven by absurdist architectural backdrops and LSD dreams.

That said I watched the entirety of the show in 4 days. My review is invalid.

Not a "good" anime, but it might still be worth watching it.

Personally, if this makes any sense, I mostly did not really like it, but at the same time I did not regret having watched it. (watched so far season 1 & 2)