The best thing about Zentyal, to me, is that it does a good job as domain controller replacement for Windows. Its good for creating domain users, and you can control permissions fine on windows servers that are joined to the Zentyal-created domain.
Ironically, since 3.2, it does a better job are controlling the permissions of a windows file server than it does its own file shares (located on the Zentyal server itself).
Thanks for suggesting FreeNAS, I will be considering it highly for my file serving needs.
Another thing I like, with Zentyal, is its gateway capabilities: Firewall, traffic shaping, port-forwarding, snat, network monitoring, VPN, web proxy.
Zentyal has a lot of good stuff, but I agree that file serving is weak right now. You'd think this would a be fundamental priority.
The fact we've had problems with this sucks, but for me the worst thing that could happen is if the domain controller got screwed up on an update (where users could no longer login to the domain). To me, domain controller is priority number one. If other things mess up, I can work around them easily, but if the domain controller screwed up, it would be super pain in the a$$ to create another one and rejoin all the computers to it (considering that you'd likely have to move each user's files to the new user profile on each windows workstation). At least they didn't mess this up!
SAMBA is such and important Linux project for SMBs. It has now evolved to a workable level; it just needs polish. Zentyal is super important too, because it brings to SAMBA a UI that bring the power of SAMBA to people who wouldn't try it without some type of GUI to configure it.