I can't speak for FreeNAS specifically, but ZFS on FreeBSD is quite reliable. There are a bunch of very smart people, in the FreeBSD community, working on it right now. I don't use it at home but I'm involved with commercial products that do use it, at my day job. If I had to choose between traditional software RAID, hardware RAID or ZFS, I'd pick ZFS any day.
Now, ZFS might not be the best solution for some. While it has many advantages over traditional RAID and other filesystems, you still have many of the same negatives that come with using traditional RAID. For example, you pretty much need to always use the same size drives. You also cannot extend the size of a RAIDZ (you can grow it by replacing the drives and you can expand a pool by adding another RAIDZ but you can't add drives to an existing RAIDZ). Those are some reasons why you see a lot of people using unraid and whatnot around here.
(without redundancy) and it ate my data
Did a drive fail on you or did ZFS really cause you to loose data? If it was the former, then you can't blame it. After all, you said it yourself... 'without redundancy' and based on your next sentence, it also sounds like 'without backup'.
Originally Posted by etheesdad
ZFS data recovery is a nightmare
It's quite easy. You just restore your data from your backup
RAID(Z) is not backup. Trying to recover data from a failed array is going about it the wrong way if you ask me.
This would be RAID-Z over two 2TB drives
A mirror. RAID-Z requires 3 devices.