I think this episode was summed up by Scootaloo when she said "Is it wrong, I feel sorry for her."
I think this was an amazing episode. It had a whole bunch of great songs without feeling rushed, and we finally get to see some character development with Diamond Tiara, it's about time. I think the CMC's cutie marks fit them well. I'm glad they made it so that their story arc is obviously not over. All in all a great episode.