It is kinda funny and has a lot of cuteness. It is just a filler special though and you don't really need to watch it.
If you do watch it however watch it before season 2 but after season 1. It won't make sense chronologically otherwise due to events that take place in season 2. I know this because with it being labeled as episode 13 I did not follow that advice that I just gave and watched it after season 2, so I do know what I'm talking about in that regard.
Most of the episode has to do with Myuu's cuteness, or funny antics between Shia, Yue, Tio, and Kaori. Mostly centered on Yue. So it's kinda entertaining. Totally filler though. So don't expect much. If you love Arifureta and just want to see some more of it then go ahead, you're probably the target audience.
