I´ve never taken Beverly Sills seriously; with such a name, and the pictures I had seen of hers, I always thought she was a kind of operatic Carol Burnett with Mado Robin´s throat.
I haven´t really changed my mind, just though noticed she was a very good singer, with quite a broad voice, which she was able to use for fine musicality.
Her performances in the MET are legendary (her trade marks being her roles in Manon, Roberto Devereux and La Fille du Régiment). A fine Strauss Singer was she also. Fantastic should have been as well her appearance in the Muppet Show. A review from her website:
I haven´t heard her Pigoletto yet, but I can offer the Aria "Ah! Vous dirai-je, maman - Varations" from Adam´s Le Toréador, where she has plenty of opprtunities to show off her coloratura.