For those like me who started with the TV version and are going back to check out all the preexisting OVA/ONA material, (minor spoilers if you haven't and are starting with this one) this basically is just an alternate version of the end of episode 6/beginning of episode 7 of the TV run. I'm not even joking, like I had to double check to make sure it wasn't 100% identical. The art style, fight content, even the ending music is completely the same, there's just enough differences where it's clear they wanted to expand in the television incarnation. If you have seen the tv run andenjoyed it, you will enjoy this because you've practically seen it already. If you didn't enjoy the tv run of kyousougiga you will dislike this for the exact same reasons, because you have basically seen it already.
I did like the TV run, and it was interesting to see how set in stone some of these scenes and concepts were at this stage in development, but I'm rating this "mixed feelings" because it really does only have clear benefit if you liked the tv run and wanted to look deeper.
On it's own? It's kinda a mess, it's a one-episode condensation of what would become the climax of a full series, that also tries to fill in some of the exposition that would be more fleshed out in separate episodes later.