I was never a big fan of Friendly, but I can tell you from my experience in the social space that Facebook is notorious for changing crucial parts of the APIs that everyone uses to pull and display information from the app. They make these changes regularly and without warning. Each time it sends hundreds (thousands?) of tech companies into a war against time to adjust their code accordingly before users that don't know any better simply become frustrated and stop using whatever it is that they are experiencing the problems on (and in this case, go on a 1-star rating bonanza).
I understand that Facebook reserves the right to manage their code as they see fit and that notification to developers is probably an impossible proposition since they make changes so regularly. It is just sort of a fact of life for 3rd party devs at this point. Users just need to be educated that you can't always blame the guys who made your app, rather the source of the data they are simply displaying.