interesting project - is it yours (judging by your username)? and if so, how's it any different from facebook? do you put more intimate information on it and befriend less people?
It's different in that it's not a social network: I don't want friending, I don't want engagement, Facebook also does personal communication in a great way. I just want it to be a good source of basic information on who someone is; answer their question and get them on their way. Another difference is that (partially due to optimizing for engagement) elsewhere it is easy to find someone's most recent actions, but it's also easy to miss out on bigger long term things. I dont want it to be chronologically sorted in such an extreme way. As I say: find out who someone is, and not just what they had for lunch.