I received my first friend request from someone I'm working on a trade with. What does this feature actually do?

I didn't know about this feature until now and navigating to https://deckbox.org/users/<username>/friends just provides me with lists and some suggestions. But it doesn't explain what this enables etc. Do friends see private inventories? Can we filter trades to people in friends lists? etc. etc.

Thanks

At minimum it adds your friend's deck updates to your News Stream; there might be additional functionality to it that I haven't discovered.