This pairing of two totally idiosyncratic vocalists acquired legendary status over the decades in which it had been out of print.
But the proof is in the listening, and frankly it doesn't represent either artist's best work.
There is certainly a powerful, often sexy rapport between the two -- Charles in his sweet balladeering mode, Carter with her uniquely keening, drifting high register -- and they definitely create sparks in the justly famous rendition of "Baby, It's Cold Outside." The main problem is in Marty Paich's string/choir arrangements, which too often cross the line into treacle, whereas his charts for big band are far more listenable.
Moreover, Charles' sweetness can get a bit cloying, too, although some of the old grit emerges on "Takes Two to Tango." [Some reissues add the great, rare B-side to the "Unchain My Heart" single, "But on the Other Hand Baby," and two excellent if unrelated album cuts, "I Never See Maggie Alone" (1964) and "I Like to Hear It Sometime" (1966).].