OpenMediaVault is a great choice for almost anyone who wants to build DIY NAS server. It's a powerful system (based on Debian) with clear & eye-friendly web interface. Since I have successfully configured my own NAS couple of months ago it's just a rock-solid.
The most recent OMV version (2.x) is still based on Debian 7 (released in May 2013) which may not be a problem if you're hardware is like the Debian itself - not so fresh, but stable. In my case the hardware (motherboard) was too young to be handled problem-free out of the box. The only way out was to update some packages to theirs corresponding version from Debian 8. Unfortunately, OMV 2.x does not support Debian 8 so I had to perform the upgrade manually (and to be honest - in quite hacky way which I've described here).