I like that it's easy for companies with limited resources (we're non profit) but have products/services of global interest, such as our book "The Artful Citizen" or other educational materials about US politics in Latin America countries we work there.
The product selection could be better tailored towards those needs - not just what sells best at Amazon! We use GP because their platform allows us access via multiple channels including webinars where people are more likely than email alone to read through all content offered.