I've done a little research, nothing too heavy. In brief, it's like any other herb. It has its upside and its downside. It really depends on how you look at it. It has medicinal purposes, most of which have been corroborated by research; it isn't tolerated by some individuals; and it definitely helps to widen your girth!
Medicinal Uses: Seeds are given to emaciated patients to gain weight, and to stimulate the nervous system. They can be used to improve digestion and elimination. They are also used to treat anaemia, mental fatigue, depression, poor breast-milk production, tuberculosis, fever, gout, kidney stones and low libido. Also used to relieve congestion during colds. Cacao bark, oil (cacao butter), leaves and flowers have been used to treat burns, bowel dysfunction, cuts and skin irritations. Cocoa butter is used in cosmetic ointments, in pharmacy for coating pills and preparing suppositories, to soften and protect chapped hands and lips and for inflammation of the liver or other organs.
Medicinal Actions: antibacterial, emollient, stimulant, cardiotonic, kidney tonic, antiseptic, diuretic, parasiticide, pilatory, dentifrice, emmenagogue, parasiticide, vasodilator, vulnerary.
Warning: Cocoa and chocolate contain Theobromide, a stimulant which may cause headaches in some people.