So yeah I finally finished the entirety of MLP:FiM over the course of about 10 months, and the ending was very good. "The Ending of the End" was a very dramatic episode with a very good conclusion and I thought it was pretty interesting how they revealed that Grogar was actually Discord in disguise the entire time although his justification for freeing Tirek, Cosy Glow, and Queen Chrysalis was pretty weak and not understable/relatable. It was pretty cool how they brought back the Wendigos and had the Young Six uniting a huge crowd of ponies and other creatures to defend the Mane Six.
So, I was sorta spoiled that the first two episodes of Season 9 would be "The Beginning of the End" in which Celestia and Luna announce their retirement, and that the final three episodes would be a two-parter "The Ending of the End" in which three major villians, one of whom would be Chrysalis and I assumed the other two would be Tirek and Sombra, would wage a huge war on Equestria, and I knew the final episode would be "The Last Problem" in which Twilight looks like Celestia and everyone else is old, and she advises a younger student called Dawn, and it would end with a song "The Magic of Friendship grows". I had seen what the Mane Six looked like. I also had seen that a major character would die and presumed it would be Celestia, but it turns out this wasn't true.
I especially liked Chrysalis during this season and I thought it very humurous when Pinkie Pie absorbed Discord's magic. I was also spoilered that the three villains would be turned into stone at the end. I was honestly quite surprised and even disappointed that most of the final episode is just a flashback of the coronation, since I knew there'd be an episode set in the far future called the "last problem" yet most of it is just memories of a problem that already got solved and we only get a few minutes of seeing characters in the future. I thought it was nice that Applejack and Rainbow Dash are implied to be living together / married / in a relationship in the last episode and also thought it sweet that Fluttershy and Discord are still close friends. The ending song was a very good one, and it was good to see so many ponies such as the Young Six and the Cutie Mark Crusaders having grown up for real. Though I guess it's a disappointment that we don't really see Cadance, Shining Armour, and Flurry Heart although we do see a grown up Flurry Heart in a stained glass painting in Canterlot Castle. It was also kinda nice to see Flash Sentry and Sunset Shimmer in the group shot at the very end though of course I do wish they were slightly more featured. And of course it was so great that they finished with the closing of the book that we see in the opening shot of season 1 episode 1 (though maybe it would have been good if they ended with a narration like at the start of that "Once upon a time in the magical land of Equestria....").
So yeah I finished this show and it was the best show ever even better than Teen Titans Go and it's going to be my comfort show to rewatch for a long time to come. It was wholesome, it had well written characters and episodes, it had songs so good that I listen to them more than "normal" music, and it has perfect animation too. I do feel that the the earlier seasons (1-4) were generally much stronger than the later seasons (5-8) but 9 was good too. I also liked the equestria girls franchise a lot and MLP: the movie was decent.