The published version of the painting looks candy colored and bright; this is partly due to printing techniques. The flat, brightly colored inks are not quite the same as the subtler watercolor and gouache used in the original.
The piece seems to have been a family favorite, as it was exhibited along with other examples of Neill's work on several occasions. One example is a 1965 display at the Port Washington Public Library, on Long Island (brochure shown below). Four paintings from Peter and the Princess were included in this exhibition, along with other drawings and sketches by Neill. I would love to know what the condition of this painting was at that time!