I am currently testing the development version of Zentyal 4.1. I have tested various Linux distribution made for Server such as ClearOS, Univention Corporate Server, Nethserver and some others. But this new Zentyal 4.1 is a promising one. Zentyal is based on Ubuntu. So it pretty easy for me to get into it. The new Zentyal 4.1 web management console has a brand new look. It much simpler than previous version I ever tried. The Dashboard page gives detailed information about the server and devices status.
User management, domain contoller, file sharing and VPN are the features that commonly used by most SMB server. Those features are available and easily configured via web management console.