It was a great start to the season. Discord was perfect to every detail, including the voice actor. The plot was great. I really enjoyed the personality changes of everypony, especially Fluttershy. That tail snap, tho. Rainbow Dash is a punk in my book now. I saw Fluttershy resist Discord and I fully expected RD to straight out fight him but she just punked out. Applejack's shifty eyes were great as well. I can't see what happens to Twilight Sparkle, and I especially can't wait to see how they defeat Discord.
I didn't like the tone of the episode up until they got into the maze. It was far too melodramatic. Celestia in particular struck me as off. Mixing chocolate rain and dramatic overtones just doesn't work. Everything else, amazing. I thought the maze scenes were all done rather well, although I still disagree with the elements. Discord is a boss. I wonder who took his in the steam group. Can't wait for the next ep.