[please move to Feature requests]

The current features already look promising. Getting the friends, their scores, downloading user images.
However, one of the most valuable features would be sending and receiving requests. That's how games can best utilize facebook to gain reach. Many don't like if apps post to their wall. Requests are less intrusive and can be used to send your friends something of value.
Famous example: On Candy Crush you can send your friends lives or ask them for lives or to unlock the next episode. Players help each other out and by this the reach of the game is expanded, because the facebook integration will make the game easier for players.

If you could find a way to integrate this to the Facebook class, it would be truly awesome.