Looking at this as a replacement for Linux on my servers. Following information compares to Debian Jessie (We've been using Debian for 10-15 years, maybe more).
Much more difficult to setup than linux (though installation is a breeze). Feels like we've jumped back in time 10 years. Kind of crap on the Desktop UNLESS you install GhostBSD, which is really pretty and straight forward to install.
However, very, very stable. Even more than Debian pre-Jessie, which was one of the most stable server platforms I've run into in 40+ years of IT work. So far, no problems except those I've created by trying to make BSD fit into my Linux mode. Just install, and start running. Update every once in a while. I upgraded from 9 to 10 then to 11, and it was what Debian dist-upgrade wanted to be.
Best of all, it only installs what it needs, with no dependencies on things just because someone thought it would be neat. And, no System-D (which has trashed some of my servers, thus the search)
Freakin' excellent documentation, and the community seems very helpful.
Not only is it a UNIX descendant, it is also well documented, source code is clean, and has a huge software pool. The fact is that FreeBSD is stable, straightforward, and doesn't get in my way. Also, no accursed systemd.