I liked Yellow.

True Pacifist was trying to show Clover deciding it's the Monsters who needed Justice more, Kill the Fox only route is kino and canon, neutral has a cool boss fight and I liked Flowey in it, Genocide has that kino moment where the robot apologizes to Clover for killing a kid an it gives his a rage boost.

I wish Genocide has an ending that still fit into canon, I liked everyone except the vampire who it feels never really got a plot line. Used the existing characters well. It has some pretty sprite work and I want to fuck the Squirrel.

Overall if you get to Snowdin and don't like it feel free to drop it guilt free but I played it between Ch 3 and 4 of Deltarune and considered it a fun addition.