I didn't notice earlier during the list-fest that I'm even more at odds with everyone else on Feeling Pinkie Keen than on Mare Do Well.
What is it people don't like about the episode? The only thing I can find wrong with it is the non sequitur of an Aesop right at the end ("you have to choose to believe").
I have Feeling Pinkie Keen at just about middle, I like it for all its cartoon gags, but don't like the way it portrayed Twilight. The aesop of "Some things just are, no matter how odd it seems" is a good one, it encourages exploration and inquisitiveness as to why such a thing could be, but Twilight goes through the episode denying what she sees herself. Which seems a bit at odds with the more curious Twilight we see in most episodes.
Mysterious Mare Do-Well is a different story. I do like the superhero references, and the ponified Batman the Animated Series logo was funny. Te problem with the episode is that it makes the mane 6 sans Rainbow Dash look jealous and spiteful Where did the friendship go? Somepony should have taken Dash aside for a moment and been honest with her, like say, Applejack. Not set up some huge elaborate prank with a madeup superhero just to make Rainbow Dash jealous. Just tell her that what she is doing is commendable, but she should watch out for letting it go to her head. Or not jump problems bigger than she could handle. Like the dam about to crack. Mare Do-Well or not, that was a "Must get Twilight! NOW!!" situation that Dash completely messed up because the other five had driven her crazy. So, yeah, like the superheroics and action scenes, don't like the little spiteful ponies.