This was definitely an amazing start to the new season and made my expectations for season 9 even higher! As much as I love this show, somehow I never quite expect something this great! I guess this calls for a review of sorts, something I haven't done in almost half a season!
Seeing all those villains return was great, I enjoyed Sombra's appearance a lot more than his first one (he wasn't among my favorite villains in MLP earlier). The others had a smaller role this time, but it was nice to see Grogar for the first time. Cozy Glow acting like a normal filly at times was fun (and I've always liked how that contrasts with her villain side), and I also found Chrysalis' reaction to her telling her to say something positive about ponies hilarious! The chemistry between the villains was definitely something entertaining!
Getting away from the villains, I thought the episode plot was very interesting in general. Celestia and Luna retiring sets an interesting tone for the last season – seeing how Twilight and her friends cope with this, other than her typical twilighting (), will be fascinating – and it would be interesting to see Starlight in her new role too (which I'm pretty sure will happen at some point). The Mane 6 were great in this episode, I have to give a special mention to Pinkie. In spite of her being my favorite pony in the early seasons, I feel her recent portrayal has been slightly hit and miss. Not this time – they showed her being the adorable, cheerful pony she is (and touchingly, also her temporarily losing that personality), even including some of her typical randomness (the cakewalk), without making her annoying at any point.
The emotional moments were easily the highlight of the episode for me. I'll readily admit Discord's speech made me cry – in all its simplicity, somehow it became one of the most effective scenes in the whole series. As for the negatives, maybe it's in part because of the show finally being back after a hiatus, but I can't really think of any. Besides maybe the lack of a new intro (it would have been fitting for a final season), but maybe we'll get one for episode 3, like we did last season. This episode deserves a rare 10 out of 10 – if the rest of the season is anywhere near this good, it will definitely be one of the all-time best!