Ability to expose services as SOAP; which in turn are easily customizable and can be consumed easily in clients own custom application
The overall reporting approach with jasper is little cumbersome to customize; especially for stuff like custom content types and custom tagsets.
Knowledge taxonomy structuring, Creating custom reports for business users, etc.
KANAs tag based approach is very helpful in creating the knowledge taxonomy. SOAP services can be easily customized to get the desired response. Ability to have single sign on authentication based on SAML, cookie based, etc.