I build a zfs based NAS last year[1], after 10 months of usage, I have nothing but positive things to say. One thing I didn't understand conceptually at first is that ZFS is standalone and not dependent on the host OS. This was not clear to me and it is not explained anywhere. You can wipe out the entire OS, move the drives to a new system, mount them on a new OS and run `zpool import` to import them. All the information (raid config, snapshots, etc) about ZFS is stored on the pool itself and not on the host OS, especially if you have an alias setup for invidivual drives in `/etc/zfs/vdev_id.conf`.
There is no need for FreeNAS or any of that stuff, I don't use all those features. Just run like 3 commands to create a zpool, install samba service and that's all I need from a NAS. Cron job to run a scrub every month.
If ZFS file system made a sound, it'd make a satisfying and reassuring "CLUNK!" sound.
[1] https://neil.computer/notes/zfs-raidz2/