I have been using FreeBSD for years, often as a development environment and testing environment on older hardware (servers, laptops etc). FreeBSD excels because it is so performant it can run well on older machines and usually supports most old hardware as well. Version 12 does not disappoint. 12 has managed to avoid the bloat and slow demise as some Linux distributions do when newer versions come out. I've noticed that newer versions of Ubuntu desktop require more and more modern hardware power each iteration, but FreeBSD 12 runs just as well as previous versions. Review collected by and hosted on G2.com.
The biggest problem with FreeBSD 12 is that to upgrade from 10 or 11 you have to re-install the whole operating system. There are facilities for upgrading in place, but when I tried this it failed. I ended up having to re-install the entire thing from scratch because the in-place upgrade fried my previous version. Review collected by and hosted on G2.com.