LDAP by its nature is lightweight and fast. It's structured for hierarchical access to user information and easy to search based on all of this information. It also has support for an SSL protocol (LDAPS) which I highly recommend. Also it has huge community of support. Review collected by and hosted on G2.com.
It does not have inbuilt user interface, so you have to be a skilled person to operate this. And It only supports LDAP protocol while other Directory Services support much protocol such as Kerberos Review collected by and hosted on G2.com.
