Overall, I don't have many strong feelings about the finale. The plot was kinda easy to predict, but it had fun moments, and it was nice seeing some new characters get some spotlight time for a change.
But, one thing left what feels like a permanent bad taste in my mouth: The changeling redesign.
I'm just trying to wrap my head around the why of it. The creators have given the fandom small nods all through the series to acknowledge and thank us for our support, so they can't NOT know how popular the changelings have been. So why have the creators now gone and taken away all that made the changelings cool and interesting creatures?
Let me break it down a bit further. Changelings represented, at least to me, a more faceted angle on the pony universe.
The show style is overall pretty uniform, round shapes and candy colors. Against that background, the changelings were a welcome change. They weren't unappealing by any stretch, the amount of fanart that exist should be a testament to that. But they had that little edge, that little feeling of otherness and danger that gives opportunities for some great character exploration.
Same goes with the character traits and interactions. Aside from the obvious big villains like NMM, the worst we really saw prior to the changelings was really about par to schoolyard bullying. Nothing wrong with that, BUT this only really added to the appeal of the changelings. Because they are the grey area. Chrysalis was clearly a villain through and through, but take an average rank and file changeling, and how 'evil' were any of them really?
Literature and pop culture has long since created a stable trope of 'a noble vampire'. Not always a literal vampire, but a character that has morals, who doesn't wish to harm anyone, but has no choice if they wish to survive. Now think of changelings as the vampires of Equestria, they feed on something essential to the other creatures, whether that's something physical like blood or less tangible like love. Not because they are mean, but because they have to. They have the potential to be the greatest ANTI-HEROES of Equestria.
This is the kinda stuff that gets me invested, because it gives my own creative side something to work with. How will an individual changeling feel about his part in the Cantelot Wedding? Guilty? Vengeful after being treated with prejudice in the past? How would he act afterward, when they've all been blown away and scattered? Would he be trying to return to his queen and happily take his place in the hive, or if he was unhappy before, strike out on his own?
This whole redemption thing doesn't leave those kinds of loose ends for the imagination to grasp. The idea of all changelings being good now and not needing to feed on love anymore might be satisfying in the short term, but it doesn't have the kind of interesting setup for how one individual might deal with a situation he finds himself in. I would have been okay with the good part, just leaving their need to feed would have made an interesting premise for their future interaction with the ponies. But as is, there aren't any blanks there for me to fill. They might as well be just a another community of ponies now.
As for the new visual design... I'm trying really really hard to come up with something to say besides 'What the HAY?' and I'm drawing blanks.They're good now, so they have to be sparkly and pastel colored? Thorax was one of the good guys in 'Times They Are A Changeling', and we didn't need him to be painted with sugar frosting and sprinkles on top to get that! There were some elements to the design I liked, like the new wings and Thorax's horns, but overall... It just seems excessive, tacky and grossly playing into stereotypes. I'm not a fan.
TL;DR: I would've liked the finale, but a complete redesign of one of my favorite things in the pony-verse ruined it at the last moment.