Okay so basically... It's a more loli-ised version of the loli...
General: Not gonna really bother with the breakdown, as it is 90 seconds long, so I'll just do the scores then the overall.
Story: 4.5/10, so 5/10.
Art: 5.5/10, so 6/10.
Enjoyment: 5.5/10, so 6/10.
Overall: 6/10. Probably closer to a 5.5/10. Basically, it is really short and a non-canon, this is sort of but not really cute version of Youjo Senki. It doesn't really work for this show, but I'm glad that it at least wasn't like the SAO one because that ended up going on for far too long, but this is only episode 0.
Honestly, I guess I'd recommend it as it is literally just 90 seconds of your life, and I have seen worse things that were a full anime, this is just bland. Only watch it if you are really starved of Youjo Senki as you wait for the movie. I am unsure if I'll enjoy the actual full series, but I'll give that a go too.