The most valuable features for our company are the Outlook Connector, which provides Exchange-like options, such as the global address list. The Outlook Connector can be configured as an Exchange account on phones (both Android and iOS). This provides access to the address list and calendar, dynamic distribution lists (which are automatically updated independently of given parameters), and LDAP authentication.
We are going to configure single sign-on so that corporate users will not need to enter their log-in credentials each time they try to access the web client from domain computers.