okay so watching it several times later here's my thoughts
pros:
interesting concept, fluid animation, some pretty nice character designs
cons:
I can definitely see why this is being called the Tumblr movie, there are very clear Tumblr vibes going on here, particularly in the way characters are designed, for example this
is clearly mettaton or at least inspired by him, this is only one character though and a lot of them share this quality
also like I said it's very hard to distinguish details in either the characters or the background sometimes due to how much they just blend in with one another, I didn't know that the mettaton guy had four arms until my fifth time through
there also isn't any noteworthy voice acting and the music is bland as forget
it's nice an animator is coming out with a "movie" (tbh I think it's just a long-ass short story) independent from any big studio but I'm not going to sit down and watch this any time soon