I wouldn't necessarily call the faces "grotesque", but they're definitely at odds with the art style of the rest. I'll grant that it manages to work for Wriggle, though.
In general, I liked the plot(even if it's not particularly Touhou-like), but that ending makes it seem a lot like the author was simply unable to figure out a natural way to give it a good ending(at least not without inflating the page count even more) and just went with the first thing that came to mind that didn't involve destroying the human village.