yes, when we started with Retrospring in 2015 it was even running on a FreeBSD host. These days however it's running inside podman containers on Linux hosts.

From what I remember it was mostly nice, we had a lot of services running on it in jails (even some native proprietary Linux® binaries like game servers), and it was quite performant too (though we had to tune it a bit to get to that point -- luckily the manpages/documentation are decent for that). It also introduced me to ZFS, a really cool file system!
The less nice parts of it on a server was running certain non-packaged complex 3rd party applications like GitLab, updating it was always a bit involved as some native rubygems didn't really build on FreeBSD (I think it was some grpc/protobuf stuff -- fueling my disgust for anything Google even more :D)
And updating the system in general was always scary and a bit more involved too, with having to rebuild the base system, rebooting it to finish the install, and then rebuild/reinstall everything as the ABI might have changed.

I also had it running on some Sony Vaio laptop I had at the time, using it as a desktop OS was a bit weird (e.g. when it comes to connecting to WiFi networks -- at the time I used it there wasn't anything that was as nice to use as the NetworkManager widgets from several desktops). Interestingly enough I had less trouble with my NVIDIA card on FreeBSD, it even performed better than on Linux. Fun fact: before that FreeBSD install I also rocked Gentoo on that laptop -- the compile times were much faster on FreeBSD, probably due to it using clang (or maybe it was doing less in the kernel in general, I don't know).