Consensus on Bartlett Sher's new production of this Donizetti charmer, which opened the Met season last year, was mixed: an unusually thoughtful conception, but muddled in execution. Still, Anna Netrebko's performance was roundly praised; she returns now in the company of Ramón Vargas, Nicola Alaimo and Erwin Schrott, with Maurizio Benini on the podium.