The English National Opera’s current revival of Calixto Bieito’s much-hated 2001 production of Don Giovanni is causing critics and opera devotees the world over to wonder whether those involved in the show have taken leave of their senses. Mark Stone, who has the lead in the revival, doesn’t quite see what all the fuss is about, but as he reveals in his online diary leading up to opening night, he’s more than a bit nervous about his decision to accept the role.