Lesley Chow at The Current:
What’s exceptional about the film’s use of the tune is that it is a love song sung under duress, not for courtship but to appease the whims of a leopard named Baby and an equally unpredictable woman (Hepburn is as much a principle of chaos as any wild creature). The song must be performed in the exact style and pace that accommodates the leopard’s movements: a harried and desperate version when Baby wants to jump out of the car; a few dawdling, absent-minded phrases once he’s safely on the estate.
The song is finally sung in its entirety when Susan and David attempt to coax Baby down from a neighbor’s roof. For once, the couple are in sync. David is beginning to warm to Susan’s bizarre charms, and the two perform a serenade, complete with discreet harmonizing.