I've been waiting to do this episode review ever since the song was leaked, and I have to say that it more than made up for any previous character-episode disappointments ("Read it and Weep" and "Mysterious Mare-Do-Well", I'm looking at you). This is the first truly serious look inside if how Pinky Pie's mind really works, even counting "Baby Cakes". To be honest, if every character-focus episode was of this quality the series would be darned near flawless. I'll take it bit by bit here.
The opener and song finally show true and major character strengths, rather than just "You are so RANDOM". Even in "Elements of Harmony", where her Element of Laughter first came into force, we never quite knew HOW she did it. Turns out it's not all completely random, just a real gift for remembering details, seeing EVERYONE as a friend, and another gift for composing songs on the spot. The song itself... well, it was beautiful. Daniel Ingram's creative talent is in full swing, and the lyrics continue to show us the inside of Pinky's world-view.
"There's only one thing that makes me happy, that makes my whole life worthwhile/
And that's when I talk to my friends and get them to smile"
This explains SO MUCH about the character, and I will admit to shedding a Manly Tear when I heard it. Every flaw and quirk about her can be summed up by those two lines (ok, maybe not her 4th-wall breaking ability). She chatters so much because she considers everyone her friend and talks to them. All of them. Her random songs actually are made up on the spot (or pre-rehearsed for specific use, like the Welcome Wagon song she sings later in the episode). The chases are just her determination. Her ability to say the right thing at the right time comes from her exhaustive study of her friends and memory. The fact that we got a Brohoof come onto the screen was just icing on the cake.
The post-song episode was also very good, giving us a tailor-made chance to see Pinky when she actually has to go through EFFORT to be... well, Pinky. CDD is also an ideal antagonist type for the series, that is to say a redeemable one (see also: Luna). Even given everything working out, she still ended up learning a good lesson and wrote a very solid letter to the Princess (unlike RD...), one lesson which she really needed to work on.
In summary, watch it. It's good