In the beginning, what made us crazy for Barbra was her vulnerability, her tendency to feel too much and take refuge behind shaky, fast-talking bravado. But the decades have been kind to her, dulling the jagged wounds of youth and upping the woozy, orchestral arrangements. Hence the downshift here: teaming up with Diana Krall, quartet and all, to get back to her jazz roots. Only, not so much. The orchestral versions get pride of place, and while there are moments of great intimacy -- when Streisand laughs her way through a phrase, for instance -- the shell, at this stage, is hard to crack.