Only the first three chapters are out, but hoo boy is it badly written. I don't know how much it messes up Haikyū canon, but the bullcrap it commits to TouRabu canon I do (and the fact it crosses these continua together alone is already more than a little sus):

• Ōkurikara (TouRabu canon) is the older half-brother of Shōyō Hinata (Haikyū canon). Let that sink in for a moment. Ōkurikara is a sword. How can a sword have any degree of biological relation to a human? That's not to mention said sword exists in real life as well! Before you ask, no, this fic is not AU on TouRabu's side, they still have a Citadel, still have a saniwa, and are still commanded into battle.
• TouRabu is canonically set in 2205, Haikyū is probably set contemporary to its publication year. The continua are 2 centuries apart!
• The touken danshi forces are called a "military" even though it clearly isn't, and post-war Japan doesn't have a military.
• Ōkurikara changes his name to "Yuki" for no reason, while all other swords keep their names.
• The Citadel is called an "HQ" and a "base".
• Tsurumaru calls Kuri "Kara-Boya". This doesn't make sense, and the actual address in canon is Kara-bō.

Aside from that, the usual: bad SPaG, bad dialogue, bad idea, bad plot. The upside is that it's actually funny in its badness, rather than infuriating like that Harry Potter crossover.

Yeah, the characters felt a bit off and there were pacing issues for sure, but not in the sort of hilaribad way that makes a good mission, IMO. The animation seemed good, so it's not the video equivalent of horrible writing. I just don't think it would be worth the effort to spork it.

Not to say that sporking a fan video could never be done—still frames and/or short clips could be utilized as "quotations" within the usual mission format. But, y'know, pick something really bad.

~Neshomeh

So it's okay I guess?