Google runs an issue tracker for the Google Plus API. Look at the 100 top rated issues here.
https://code.google.com/p/google-plus-platform/issues/list?can=1&q=&sort=-stars&groupby=&colspec=ID+Type+Status+Component+Owner+Summary+Stars+Opened+Modified+Priority
It's enough to make you wonder what the issue tracker is for. Because it really doesn't feel that the G+ API is progressing much or that the issue tracker serves any real purpose.
I wrote about this 12 months ago in a previous post here. https://plus.google.com/106416716945076707395/posts/VDBxM9KtQUm The API hasn't changed much in that time and neither have the outstanding issues. We've had a change of leadership of G+ and some new features and enhancements in the various interfaces but this isn't really reflected in the API.
+Thor Mitchell +Rowan Merewood +Michael Stillwell +Joanna Smith +Ade Oshineye +Fabian Schlup +Abraham Williams