Highlights — from my perspective — include:
* The bsdinstall(8) utility now supports UEFI+GELI as an installation option.
* The bhyve(8) utility is now able to be run withing a jail(8).
https://lists.freebsd.org/pipermail/freebsd-announce/2018-December/001856.html
https://www.freebsd.org/releases/12.0R/relnotes.html
PS: There’re a few days left to purchase a FreeBSD 25th Anniversary t-shirt:
https://www.customink.com/fundraising/freebsd25