Well is massive, there are some good and bad aspects to be said, for one "standard" Pinkie Pie is just not very good; is non-canon, exaggerated and fastidious, terribly annoying to read and painfully written considering Pinkie's canon demeanour.
But in this chapter Pinkie's personality is completely fragmented(pretty Freudian) and thus it creates several characters that interacts with each other conforming Pinkie's personality as a whole, I know I'm stating the obvious here but is important to consider that each part of Pinkie has its own identity and almost its own character(which depend on what of Pinkie's psyche is used/embed). Parting from this I must say that "Pinkamina" is the real protagonist in this chapter, I can recall that she might be a lead on her psyche (given that she had dominance in Party of One) but I cant figure out if she can play out the things that happens on that chapter, seeking control of the situation might be one of "Pinkamina" characteristics, but there is stuff like saving her own psyche elements from "Angry Pie" which doesn't make much sense to me, giving it the benefit of the doubt I will say that probably "Pinkamina" knows more about Pinkie Pie as a whole, because of being the part that was active during her childhood.
The whole scenario was pretty clever too(considering the stuff in the AJ episode, I'm actually quite surprise that the writer also came up with the whole concept of "Pinkie's psyche scenario"), the whole thing reminded me a lot of The End of Evangelion(everything being one, inner psyche realization, self awareness, huge alter ego/ego ID fights, everything was pretty much there).
In short words, a pretty cool episode, Pinkie Pie's standard character is pretty weak if I'm honest, but the rest of the story manages to subside this problem, and how the events were managed was pretty original, it doesn't leave the theme of "inner-fight" but is still more interesting than whatever bipolar disorder comes out of writers these days.
Here comes Pinkie...
