During previews, I had a good experience during the Saturday evening performance in the rear mezzanine. The only thing that struck me as highly inappropriate was a single absurdly loud "Awwwww" when a particular emotional scene occurred. I did notice that the ushers seemed a bit lackluster, though. They didn't deliver any warning about phones that I saw, and they seated people at odd times when they arrived late. Not during musical numbers, but halfway through some scenes.
BROADWAY: The Cripple of Inishmaan, This is Our Youth, If/Then, Hedwig and the Angry Inch (x3), Cabaret (x2), The Real Thing, A Gentleman's Guide to Love and Murder, Chicago, Les Miserables (x2) Disgraced, Finding Neverland, On the Twentieth Century, Wolf Hall Part I, On the Town, Fun Home; TOURING: Jekyll and Hyde, The Book of Mormon; LOCAL: The Twilight Zone, Anne Boleyn, Death and the Maiden, The Lying Kind, Chorus Line, Stupid F**king Bird