1. Access is limited: A URL was published, then quickly went dead. According to a comment by Irving Leonard, access to Redsocial is confined users on a "/8" (up to 16,777,216 hosts) local network that connects Cuban universities. In this Redsocial is a clone of Facebook when it was first launched -- restricted to a few univerity students.
2. Size is limited: Redsocial claimed 7,000 users had registered up in one week. One tenth of the world population uses Facebook.
3. Facebook is a platform: I did not get a chance to see Redsocial before they cut access, but I would be amazed if it provided anything like the open development environment, which allows one to create applications that are used inside Facebook.
4. Anonymity: One can create a Facebook account without divulging their real identitiy, but if one must access Redsocial through a university account, their identity is discoverable.
If Redsocial is a Facebook clone, it is a clone of Facebook in 2004, not of today's Facebook.