Hahaha, I knew that was the plan all along. Fluttershy guilt-tripped Discord into behaving. What a pony.
They did lay it on a bit thick at the end although I loved how he said, "Friendship is magic" but all in all, I think this was pretty awesome. They also made it clear that he isn't totally reformed and that he might cause some chaos in the future. I hope we'll see him again.
I chuckled at all the other ponies' reaction to Fluttershy's monologue at the end.