INTO THE WOODS, Porchlight Theatre, at the Athenaeum Theatre. Exuberantly acted and beautifully sung, Porchlight’s latest foray into the oeuvre of Stephen Sondheim is nonetheless a disappointing follow-up to its superb revival of his Merrily We Roll Along. The subtlety and emotional honesty of that production give way here to a broad comic approach that seems inspired by the “Fractured Fairy Tales” of Rocky and Bullwinkle fame. The jokey style is fun at first, and cartoon fairy tales might seem apt models for Into the Woods since Sondheim and playwright James Lapine weave together the stories of Rapunzel, Cinderella, Little Red Riding Hood, and Jack the Giant Killer. But their complex narrative explores themes of family, moral responsibility, and coming-of-age, and director L. Walter Stearns and his ensemble don’t negotiate well the work’s gradually darkening tone and such unpleasant realities as marital infidelity and sudden death.