Directed with unexpected ripples of beauty by Joe Mantello, 'Casa Valentina,' which opened on Wednesday night at the Samuel J. Friedman Theater, conveys the blessed consummation that occurs for ordinary people when they're transformed externally into what they think they are inside...This being a work by Mr. Fierstein -- who, no matter how daring his subjects, is an old-fashioned playwright at heart...paradise will be lost through a series of carefully laid-out confrontations...The terms of the arguments here are intelligent, and sometimes even provocative. But the air often feels filled with the dry dust of chalk erasers being batted together by a painstakingly instructive schoolteacher. This is a shame. For its first half-hour or so, when 'Casa Valentina' is more show than tell, it promises to be Mr. Fierstein's most engagingly insightful play to date.