RedHen knows a lot of nifty tricks, some of which are described in the regular documentation pages, and some of which don't quite fit anywhere. This page will give you a good idea of things that RedHen does that you might not necessarily expect from a CRM, even if you might find it useful.
Connect Drupal Users to CRM Contacts
This is described all over the documentation, but it's a handy trick to know about! Read more here and here.
Dynamic filtration on Contacts and Organizations
As you add fields to Contact and Organization Record Types, RedHen intelligently makes those fields available as filters in the CRM's User Interface.
Salesforce Integration
RedHen was built by the same team that lead the 7.x-3.x rewrite of the Drupal Salesforce Integration module, and integration between the two modules has been carefully refined.