This is for comedy, nothing more. If you enjoy the actual series and its characters you will enjoy this.
It's incredibly hard to make a lengthy review of this considering it is just a short at the beginning of each episode, so my review scores are based solely on personal enjoyment and some bias.
Story -
Shiki is in the theater with you, please be respectful for safety purposes!
Art -
Just look at it, it's not the art you see in the actual series and that's intentional.
Sound -
Some meowing; I'm serious.
Character -
They add on as they're introduced in the main show.
Enjoyment -
I laughed a few times, I believe.
Overall -
Unnecessary, but entertaining!