GREASE:
Well, the duets were instructive seeing couples interacting during a song. One couple - Austin and Laura - had the best singing/acting of the five participating couples, though having a ballad ("I Don't Know Much") they sang in perfect harmony helped convey acting through singing and movement the best.
Chad (by far the audience favorite) and Allie had the best song and routine ("Ain't No Mountain High Enough") and though they put on a great show for the audience, I didn't their personal connection was as strong as some of the other couples.
Derek's rather obnoxious comments about Austin at the start of the show rather doomed him tonight, I thought, and it wasn't helped that he had the worst vocal performance of the night. Bravado is one think, but being snarky on-camera about another contestant seems pretty petty, and it may hurt him.
And Kevin and Kathleen, the couple saved by the judges from elimination, had really shaky harmony and didn't seem especially in tune with each other as a couple either. I wouldn't be surprised if they both ended up being eliminated on the next show.