I’ve used it. More just so I had a “landing page” on my NAS and pretend what it would be like to have a web GUI on a NAS
It’s OK. It doesn’t handle RAID, ZFS, or anything other than just a MergerFS setup or single disks.
I like the built in file browser, as it offers SMB sharing with just a right click on a folder. Handy for those times where you just need a quick SMB share for a bit.
That’s not what Docker is intended for