Everything with Pinkie felt like good old season 1 and I loved that. We got more Derpy and even Mjolna returned in the flashback, the final song and party are great, evoked a lot of the good old days of pony.
But Rainbow Dash ditching her friends for a third time in as many episodes felt very off, the mane6 doing the same was bad, and Weird Al as much as I may like his own work, really colosally miss-fired for me in this episode. He was shoe-horned in so badly, took over the whole damn episode, created so much hype, etc that it just ruined the episode for me.
Really wish they hadn't done this.