You'll get the benefits of Facebook (real identity with almost everyone on the platform, events, groups, etc.) without loosing hours reading crap on the news feed.
Kind of interesting, but then what's the point of Facebook? Asides from invitations - which, perhaps naively, this friend did through a post in his feed - the only thing that I'd be interested by is maintaining a light-touch connection with friends who are overseas by looking at their posts in the news feed.
Biggest use cases for me has been events and groups.
1. Events: Facebook's provides a streamlined experience for hosting events and all my friends use it for birthday parties, house warming and so on.
2. Groups: Facebook's group experience is quite good and I am a part of 4 groups of like minded people that I get to have conversations with quite frequently.
Makes sense in terms of network effects I guess. I wonder where the tipping point is when enough people aren't on Facebook so people go back to other services and / or email.