Honestly, I watched this out of pure recommendation, just because I heard it was about death metal, a musical genre that relaxes me, and frankly, I laughed. I found myself laughing many times. And also headbanging, and dancing in my panties all over my room.
If I understand this well, it's created for the Japanese branch of Netflix, I have no idea if it had any kind of occidental influence (or money) because the series has a sort of Nintendo style to it. It looks like a long-lost rhythm game for the DS if anything. A time when videogames were art.
The graphical style got me hooked on the series, these critters are cute, the facial expressions they pull, even just how they move by going from the foreground to the background (reminding me of Paper Mario, at times). The soundtrack to this series is pure bliss to my ears, be it at the karaoke when they yell a lot of METAL, or even just the ambient music that plays throughout the show.
Not displeasing to my senses at all. Even more, if one gets hooked to the esthetic of cuteness meeting its aggressive side.
The episodes are really short and no plot really gets developed. This makes the show easy to enjoy, never really a time to get bored or fill the series up with filler and bad animation. One punchline follows another, and the whole thing is coherent. The Hippopotamus was a highlight, talking some fast bullshit and moving wildly. Also, they didn't spare themselves from screaming a lot of metal, so it's all good.
Honestly, I don't know if this could ever be displeasing, it was all very stupid but never really felt heavy to me.
This show isn't deep or that intelligent, but there was some nice common sense in mockingly depicting Japanese work culture (even if the characters are very broad caricatures).