I really like human Fluttershy's design in the comic. As I pointed out earlier, I was surprised that the person who draws those comics didn't try to make her the most gorgeous girl they could. She's still really cute, but not to an extreme.
I guess they best way I know how to put it is that there's a lot of warmth to her character design and she easily comes off as more than just a pretty face along with all the other characters in this comic. I think it might be one of my favorite human designs for her.
I like the designs of the other characters as well, although I still say that humanized Rainbow Dash's would look better with shorter hair, but that's mostly just a personal preference. I also like how lively they are in all the panels, even if Pinkie is going a bit over the top in the silly stuff, but it is Pinkie after all.
Edit: By the way, this is cute and I for one support the idea of Derpy wearing glasses sometimes: