The hallmark of a professional actor IMHO is to hide behind a mask. It is jarring if the mask slips, and the actor's true personality does not match the intended persona. This is chiefly what makes school and most amateur theatricals so trying.
Metropolitan is witty, intelligently filmed and directed, pleasing to the eye, but the actors seem like high school amateurs - and like many high school plays, the male actors are unable to conceal their epicene nature - I don't have a problem with who they really are, I just want to have it concealed to ease my suspension of disbelief. As much as I liked this film, it seemed so stagey, the actors just did not convince me as they meaninglessly mouthed the director/author's acid epigrams.
I will probably rent this again. And I will enjoy it again. But I will also mutter "So fake" as the puppets go through their paces.