Bitched about here.
The author of the Wikipedia article about PGPR, in his Yelp account as "Aaron P.," states that "It has a detectable and somewhat offputting aftertaste.... American chocolate makers have been lobbying for years to be allowed to add vegetable fats to their products so they can sell the cocoa butter at a higher profit to cosmetic manufacturers. So far they have been thwarted, so now they have moved to using PGPR to lower the levels of cocoa butter while still remaining undetectable to most people." He also noted that "Unfortunately, someone keeps altering the (Wikipedia article) to detail the glories of PGPR, and I have to keep fixing it."