Any central repository of personal data and conversations is ripe for abuse and Facebook unabashedly abuses the personal interactions stored on their site. User data is supplied directly to corporations wishing to run studies on the social interactions with no restrictions to the goals set for the use of the data.
The best social network.
4 - Trustworthiness - Beware of posers,hackers,
None - Vendor reliability - i don't buy in facebook.com
4 - Privacy - It's a social network so giving information is normal but beware.
4 - Child Safety - Bot,hack account - giving a websites of porn. So Beware.