When you like someone, you might say, "She is an absolute delight." You mean you think she's great: a delight is a source of joy, and to delight is to cause pleasure. Babies are particularly good at expressing delight in new things.
Delight is often associated with an initial impression—one says, "She continues to delight us," to suggest that the first impression continues. The word delight derives from the Latin delectare "to charm," which also gives us delectable, and the same lighthearted sense of pure, uncomplicated pleasure.