It also provides the ability to synch more data (i.e. user fields, customizations) and on a more detailed schedule then most other out of the box tools.
This means that if you want to integrate your system with other systems, like your website or accounting database or if you want to perform complex customizations (and have the expertise to do so) you can dig into the entrails of SugarCRM to make it do exactly what you want it to do.