I'm a huge fan of the show, but I absolutely hated this movie. I would have liked it, warts and all, had our long-established heroes either not been barely useful at best, utterly inconsequential in the middle, or downright detrimental to their own progress at worst. Pinkie Pie getting Klugetown's attention and Rainbow Dash's Sonic Rainboom are standout examples, but I absolutely loathed what the movie did to Twilight in this film. Seven seasons and two Equestria Girls films worth of development? Gone. Completely down the drain. We get to see her attempt to steal a pearl, shout at her friends, get captured and not even really try to escape aside from some magic blasts, and then feel sorry for herself and let her magic get drained. Only when the movie reminds her that she's the PRINCESS OF FRIENDSHIP does she become useful in the slightest. Honestly, I felt outright betrayed by this movie; it took steps backwards in terms of development just for the sake of creating tension, and no movie should ever, ever do that.
I actually prefer every single Equestria Girls film, individually, over this garbage. It may have introduced some great new characters and settings, and it had quite the budget this time, but good effects do not excuse a terrible story nor character derailment. And the fact that it's all going to be canon just makes me even more sick to my stomach.
In short... FUCK. THIS. MOVIE.