Lightness is a virtue, but only up to a point. Playwright Sarah Ruhl has won acclaim by combining ready-for-prime-time one-liners with vaguely meaningful strokes of lunacy: characters chill in the afterlife, or turn into almonds out of sheer grief. "Dead Man’s Cell Phone," a play about a woman who finds a you-know-what and insinuates herself into the dead man’s family, indulges Ruhl's wayward tendencies to the point of mawkishness and gimmickry. The hype surrounding the play implies the presence of revolutionary artistry, but it's just a sentimental romcom with a metaphysical twist. It's pleasant enough, but why are we all so excited about a weirded-out stage version of "While You Were Sleeping"?