CMS compatibility ?
Static Pages ?
Secure Members Only Sections ?
Forum Intergration ?
The Basics ? Contact Form, FAQ plugin, Mail List, notification, etc
Template flexibility, appy templates to usergroups

I'm having a difficult time choosing, i really want a complete CMS/Blogging solution, seems ...

is this through the discussions plugin ? how is it suppose to work ? is there already a forum built into serendipity ? or do we have to have a phpbb install and it pulls it in ? The plugin seems to says that it is the forum unless i read it wrong